There's a lot of reasons this article is flawed, not all of which I can address. I can however address a fair few of them.
Firstly: Professor McKays book, while an incredibly interesting read and definitely recommended, simply adds up the cost of our current lifestyle and then looks for power to keep it going. The book doesn't address many energy saving measures, and so the claims that the UK would need to be packed to the rafters with wind turbines are somewhat redundant.
Secondly: Nuclear power is prohibitively expensive. We don't realise this now, because the last power stations were built over 40 years ago. Nuclear power has benefited from huge government subsidies, in the form of various nuclear related agencies, limits to public liability insurance, and because of the by products it can produce. Without such subsidies, the economic viability of it is questionable. Nuclear power is inherently linked into the government, and so benefits from a lot of public agencies. If new power stations were solely public affairs, and these costs were taken into account in the cost of electricity, then this wouldn't be so bad, but the fact that new nuclear power stations would likely be private companies means that the government is essentially giving them a free ride.
The article discusses some pretty fanciful things, like space flight, destroying asteroids and technology development. There are a number of problems with your arguments here as well.
If there is an asteroid threatening the earth, the UK is unlikely to be the one called on to provide a nuclear strike. Given that we have no space program whatsoever (due to labour and conservative governments), it is highly unlikely we would have any real input on the matter, trident or not. Trident isn't capable of destroying asteroids anyway, so the point is pretty much moot.
Without a space program, the UK is unlikely to explore other planets. This is pretty much unrelated to civil nuclear power. The nuclear power used by spaceships is very much unlike that used for civil power, and the two have very little bearing on each other. If the UK chose to not use nuclear power, it would have no effect on the development of small scale nuclear reactors for space ships.
Finally, suggesting that voting for the lib dems tomorrow will result in the entirety of humanity becoming extinct is pushing it a bit even for the register. Voting Lib Dem will *not* cause humanity to die out due to asteroids, and is likely to have no affect on any space programmes anywhere in the world (given that we don't have one anyway). It will, however, bring the electoral reform this country needs. It will reduce the number of stupid databases the government holds. It will ensure that the poor are protected from poverty, it will bring a fairer tax system, and it will bring the governmental shakeup that this country needs.
This article is mostly crap, with a smidgeon of idiocy mixed in. I understand that (for some reason) the register has a right wing political agenda (has anyone ever got to the bottom of why an IT news site catering to educated professionals is so right wing/climate change denying?), but that doesn't really mean you should push utter tripe onto your readership.