i'm a y13 who is an offer holder for medicine, but i do have a brother in his 4th yr of med school and a cousin who's an fy doctor. i can't really comment on or predict the state of the NHS in the foreseeable future, but yeah it's quite in shambles atm..
i do believe there is a very wide range of graduate opportunities if you don't want to work as a doctor after you graduate, this could be research, pharmaceuticals, idrk much though but there are definitely options. there are people who graduate and then just don't start to work as a doctor. but i wouldn't recommend doing that knowing from y1 you don't plan on working as a doctor, it just seems like a waste of time, but if you've changed your mind by final year it could be a safety net to fall on i suppose
there is always the option of moving countries after a bit though if the state of the NHS in the UK is a big concern
i obviously can't say much about work life balance from personal experience, but i have spoken to a lot of med students about this and my brother - who all seem like they do have time to do the things they enjoy yk, it is obviously gonna be quite intense but it's definitely not just work, eat, then sleep if you're efficient with what you do and disciplined. working as a doctor especially in the first few years will undoubtedly by tough though, there's no denying that, and med school is still very hard.
the passion thing is a very personal thing that will be different for everyone, especially for me as someone who hasn't even begun med school yet it's hard to answer, i do feel like a lot of people feel similarly though, it's normal to have doubts, especially when it's such a big step to take. take your time before september/october to fully decide, try getting as wex if its a hospital or GP, so u can shadow people and it might help make you decide whether you can see yourself in this profession in 5-10 years time. definitely go to open days too, even just for the sake of speaking to lecturers or current med students! you still have time to decide, i do like watching vids of current med students and even doctors doing vlogs & stuff, though i do think sometimes they're portrayed in a more glorified way than a day in their life may actually be, lol
i know i'm definitely not qualified to answer most of these questions and half the stuff i said could very well be wrong LOL so take what i said with a pinch of salt but i just wanted to give a little insight & my personal opinion since no one has answered yet, i hope this helps a bit! if you have any other questions about anything that could be within my scope of knowledge, lmk