Yes there's loads you can do to prepare and unless you live in the very centre of a busy city there is a good chance you will survive and be faced with "and then what do I do?". This "we're all doomed" mindset was great as a deterrent and to exert political pressure on decision makers to get them to step back from MAD in the 80s but we've moved on a lot from there, we're a lot more powerless to make our voices heard, and we have a lot more knowledge and understanding of nukes. For your psychological wellbeing the best thing you can do is educate yourself and be prepared (as much as you can).
If you look at Nuke Map you can see your chances of being caught in various different situations based on the size and location of any given nuke that's deployed. From Slough, the most likely target would be London so you are unlikely to be caught in a direct hit. Nukes are expensive and heavy, they won't waste big nukes on small targets.
Research "potassium iodide" and you'll find the strength and dosage you need. I got some in the correct dosage for £10 on Amazon about a month ago as the ones I bought five years ago were a lower dosage and wouldn't be so effective. You live and learn.
These videos from the Provident Preppers might help (but take the medical info with a pinch of salt, the guy doesn't know his iodine dosages at all, much better advice on that front from the NHS, below):
If you want to be mentally prepared for the very worst case scenario, and you've got a robust mindset, do also watch Threads but I suggest you immediately make a nice cup of tea and contrast it with The Day After (the US one was made first with a verrrry similar set of plot points). The Day After is on Youtube and the full original Threads is on the Internet Archive. The version of Threads on Youtube is edited to make it look like a documentary. Threads is a drama not a documentary. It is based on the outdated concept of a "nuclear winter" which doesn't fit our current understanding of the impact of a major nuclear war. Current theories are that the impact will be much less severe or shortlived and a lot more survivable.
The Protect and Survive videos from the 1980s are fucked up but you can watch those as well, just bear in mind a lot of the advice is utterly useless and designed to make it easier for them to find the bodies (there was a poem about that, which is probably no longer covered in GCSE English but was when I was at school 20 years ago). The US produced some much more life-affirming videos and I strongly recommend one from 1970, linked below.
Once you have absorbed it all, look up prepping info about how to start planning/preparing.
The more people who educate themselves instead of being paralysed with fear, the better our society will be in the aftermath if this happens. Survivors will rebuild instead of regressing if they can stay alive in the short run and maintain strong communities in the long run.
Resources:
NHS Info on Potassium Iodide: https://www.england.nhs.uk/wp-content/uploads/2016/03/supply-of-potassium-iodide-65mg-tablets-v2.00b.pdf
US video from 1970:
The old protect and survive videos:
Threads (fictional) https://archive.org/details/threads202007
The Day After (fictional)
NukeMap: https://nuclearsecrecy.com/nukemap/
Edited to add NukeMap to resources.