Most UK people are probably not even qualified to comment ...
... and I say that as someone who emigrated to the USA (Texas, in fact), from the UK.
Setting aside the smart gun idea, for now, let's address the ownership of weapons in a free society. The provision in the constitution, whose addition was initially resisted by the way (more on that, in a moment), reads in modern English as, essentially "Since a free society needs it's able-bodied citizens to be ready and able to defend it, nobody is to be prevented from purchasing and possessing weapons" - this concept taking its inspiration directly from the previous law of the land; English common law, which had long precendent of right to self-defence, and right to own, carry, and use such for it.
The "militia" is all able-bodied (and presumably, willing) men, as a body, for the defence of the community. It never required any formal organization. "Well regulated" doesn't mean what you think it means, because language shifts usage. It's close to "properly supplied and organized", in current English. It's misinterpretting the phrase "well regulated militia", whether ignorantly or wilfully, that leads to the bogus assertions that the Second Amendment is supposed to apply to the military, in some fashion (unlikely, anyway, there being no standing armed forces), and requiring 'regulation' in modern sense of restrictions and rules.
So, I said "more on that later", aye? Well, the reason it is an amendment and not in the original constitution itself, is that the "framers" considered it so obvious a right that they didn't see the need to enumerate it. The legislatures were eventually persuaded to add an amendment, over the same objection ("It's unnecessary!") because some states had begun to attempt to regulate possession and purchase of weapons, though it was mostly knives and swords, at that point, believe it or not. That's right! The second amendment never mentions firearms! It's about the right to be ARMED, in the first place, and they didn't feel the need to give special treatment to firearms.
The Supreme Court of the United States has ruled in various ways on this, reflecting, as you'd expect, the political mood of the times. Most recently, however, it has specifically re-iterated that the amendment addresses an individual right, not something granted by membership of a group, per se ("militia of one"), and that the "well regulated" provision means that citizens should have access to weapons that would be useful in defence of person and nation (in other words, if it's good enough for the US Army, etc, it's good enough for a citizen, too). It has also ruled that the amendment is underpinning the right to self-defence, and that self-defence is thus a valid reason for possessing, carrying and using a firearm.
Now, for the UK issues. If you've never seen a firearm, you might actually be in a minority. I'd dare to suggest that either you've travelled very little, or you're extremely unobservant. In rural Britain they are quite common, in Northern Ireland (part of the UK, remember?) individual ownership of firearms, especially pistols, is common and often recommended to certain persons, by the PSNI (police in the province). British police have been routinely armed for at least a decade, closer to two, in fact, and not only at airports. Once, in very early 2000s, I was returning to my home in Stafforshire, shortly after a football game (unbeknownst to me, as I never paid attention to that game). As I went to step off the train at my home station, I walked into a literal wall of armed, and armoured, police (British Transport Police), all of whom had sidearms (9mm Beretta 92s, at the time), some of whom were carry MP-5 submachine guns. I was briefly questioned about my intentions, then permitted to leave - they were preventing travelling 'fans' from leaving the train to visit pubs and get more drunk. This story is only one of many casual encounters with police who were armed, and when I actually worked for my local force, I daily saw officers who were routinely armed, and no, they were not all members of the "Armed Response Teams". By the time I left the UK, in 2011, the police officers who walked their beat around my town center all carried sidearms.
Now, perhaps you believe the police should be armed, even if other citizens (they are just citizens, same as you, remember?) are not permitted to be. I pity you, but I left, so whatever. However, you'd be shocked, then, at just how many of your fellow citizens also have regular access to firearms, especially in rural locations. A shotgun licence, even when I left, was 50 GBP, a short form sent to constabularly, and a couple of follow up visits to make sure you had proper storgae for firearms and ammunition (plus a check in with your GP). Many, many rural dwellers have shotguns, most of them probably legal (but by no means, all - lots of farmers and other rural people never complied with the legislative changes and never registered their firearms). They're out in the country, though, so no problem ... how about the drug-dealing thugs in the cities, then? I was indirectly threatened with a firearm twice during my life in the UK, in both cases the person in question was a "convicted felon" as they say in these parts, and was known to be regularly armed. In the case of one, when he was no longer upset at the imagined slight, I had occasions to see the five pistols he illegally owned, all of which he assured me worked, and all of which were modern automatic pistols. No guns in the UK? Give me a break! Safer for it? I wish!
Ah, you say, "you've been unlucky, and I have never felt threatened". Well, if so, good for you. Didn't go out much, did you? Every weekend that I went out in my youth, and even into my late 20s and early 30s, I either witnessed violent assaults or was involved in them (usually, once older and less stupid, as an unwilling defendant). This was, and likely is, so normal for much of the UK, that when I initially came to the USA, I was a little scared. After all, I'm in Texas, where people have (relatively, though by no means as easy as some think) easy access to firearms. The first few times I went out, I was on edge, but never saw any violence at all. Eventually, as I continued to socialize, it dawned on me that while Texas does have far more guns, in all likelihood, than my 'home' in the UK, people are actually *much less violent*. Guess what? The crime statistics bear this out. Sure, US gun crime is much higher than UK (more guns, most of the legal, too), it's violent crime rates are mostly lower, in reality. Especially for violent assaults, knife crime, etc. More burglaries, in some states though :(
I'm now a citizen, and even before then, I purchased firearms once I was legally able to do so. Not only for defence, though in this state, I'm permitted to have firearms in my vehicle with no special "permit" required, but also for sport at the various ranges in the area. I have what we now call a "Licence to Carry", which permits me to carry a pistol, concealed or openly (subject to rules about being properly holstered) as I wish, in most places, unless they are a private business that expressly tells me I am not welcome to do so. I am almost always so-armed, and not because I am scared, but because I believe, along with many Texans, and many in the USA at large, that "An armed society is a polite society", and because in the unlikely event I need to actually shoot at someone, I don't want to wish that I'd brought one of my pistols with me, while I hope the police arrive before I, or someone else, is killed. I've "used" my pistol twice in the time I have been here, and both uses were to show that I was armed and state that I was prepared to use force if the behaviour did not stop. Once was an abusive visitor to a neighbour, the other was someone (actually a group of three) who approached me in a sparse parking lot (carpark) with likely intent to rob me; the first case caused the aggressor to resort to hurling insults, rather than attempting to continue closing on me with obvious intent to assault, before he went back inside, as I calmly walked away. Once he left, that neighbour thanked me for stepping in. The second time, the person approaching me realized I had clocked him (and actually I had clocked his two buddies, as well), stopped short then took off back towards the supermarket, his friends doing likewise when I turned to look at them. These kinds of incidents are what others are talking about when they mention "defensive use of handgun", and I reported neither incident to the police (there seemed no real need in the latter case, though it might have been a good idea, in hindsight, with the first incident, my neighbour asked me not to, since it would cause her personal trouble and he was already known to them).
In the UK, my options in case one would have been "don't get involved" or "call the police", unless I wanted to get into a fracas, and likely end up being assaulted, and facing counter charges of assaulting him. In case two, I guess my only option would have been "try to get to my vehicle before they get to it, or me". None of those options seem to be ideal, so I'll take my gun ownership, thanks.
Oh, to my friend in "Tejas" - you can drink while armed, you simply must not become intoxicated while in possession of a firearm. We drive everywhere, though, so you wouldn't do that anyway, would you?
Anyway, I'm glad that my schooling included being taught to shoot a shotgun, at clays, when I was 7 through 13, in good old England. Where there are "no guns".
Anyway, wall of text, so thanks to those who read it.