@OMGTTC
Thank you for your responses. I’m really sorry to get in a panic about this when real people are actually suffering in the present, but your replies were really helpful and informative, thank you.
I’ve always had a sort of morbid fascination with it since I was a child, although I was born in ‘93, so haven’t lived through the times of the leaflets/sirens etc.
It's natural to feel concerned about it, because it's the worst thing most of us can imagine. In the UK, we've been fortunate to live through a long period of relatively stable national security, so many of us are confronting the idea of a threat for the first time.
Just in terms of nuclear war, we've been here before, and with SIGNIFICANTLY less restraint shown in terms of nuclear rhetoric by world leaders. Look at Trump and North Korea rattling their sabres at each other, or Nixon trying to intimidate the Soviet Union by giving the impression that he was irrational. Nobody can achieve their aims, whatever they are, in a world that doesn't exist. There's no point in being powerful if there's nothing there to exert power over.
That said, it's important never to be to casual about the potential for nuclear conflict because you never want leaders to get into a mindset where they underplay the impact and think such a war could be 'won'. In a sense, I suppose, the fear of nuclear war keeps us safer from it because it's pretty universally shared.