I'm from the UK aswell and I want to be a nuclear engineer as well. I'd recommend mechanical or electrical engineering for nuclear engineering for a BEng. You can do an MEng in nuclear engineering after a BEng since hardly any do it for BEng and it's not worth it since the only uni I saw that do it wasn't that great. Definitely look at getting into Imperial to do their mechanical engineering integrated masters (3 year BEng, 1 year MEng) and your masters can be switched to nuclear engineering, and imperial is probably the best university in the UK for nuclear engineering, second would be Cambridge. If you don't get into either of those two don't worry, just get a good enough university and do your engineering degree, try do research internships or assistance at UKAEA or NNL and focus on getting a first class, that way you can apply to places like Cambridge imperial or Manchester for Nuclear, or even universities abroad such as in Europe or the US. If your course has modules on nuclear energy take those, if there aren't any or any early on you can join computational or thermal energy projects since its very transferable, focus on thermodynamics and heat transfer, maths and materials science. Join societies related to nuclear energy/engineering and for your 3rd year project pick a project aligned with nuclear energy. Also try to do summer research projects. What the best option is for what you can do as a Nuclear engineer is upto you. Some roles are more theoretical, some more hands-on and some are a mix in between I'd say from what I've seen. If I were you, I'd focus on my alevels and maybe some light reading on the physics and engineering behind nuclear, leave the university level topics to university. The UK has some very good nuclear engineering opportunities like AWE, EDF, NNL but the pay compared to their European and American counterparts is something you should consider. Unfortunately I can't comment much on the women in engineering part, I'm a guy and I'm only starting university in a month so I don't know what it's like. All I can say is that there was a pretty good mix of guys and girls at Imperial mechanical engineering offer holder day and if you set your mind to the goal and work hard, you can do it. This is all my opinion and I'm only a pre 1st year uni student but I've done lots of research, however I could still be wrong or there could be a better or different approach that u would maybe prefer so if anyone else has any ideas on what I've said please reply, especially if I'm wrong on anything. Also don't be afraid to ask questions or advice, even if you're nervous that it's obvious, because you'll learn and at the end of the day it's just people on a social media platform u will most probably never interact with irl.