Re: What will happen during a war?
Your questions are academic until you decide who is supposed to be attacking us. (Of course we are far too civilized and kindly to start any wars).
Probably no European country. Hardly likely to be African or South American. Can we rule out the Commonwealth? That basically leaves Russia and the USA, and if either of them attacked us there would be nothing left but a pile of smoking ashes in about 45 minutes. (Yes, even faster than Saddam Hussein could have managed).
Of course there is always Israel... a nation with a thermonuclear arsenal probably larger than the UK's, whose loyalties and policies are utterly mysterious and unpredictable. And it's within easy range.
There is no imaginable situation in which an F-35, or any number of them, would do us the slightest good. Their only purpose is to enrich American billionaires - which they do very effectively indeed.