thank you! hah
well, I think it was quite tough, definitely more than my local programme where people are actually starting to work hard in the 3-4 last months before final exams, while we had to work hard throughout the 2 years, but I'd say it was worth it honestly, I'm glad I chose to do the IB although there were (and still are) times I cried, wanted to give up and hated myself for choosing this hahah but I really liked the programme, especially that it's in English (which is surely not a thing if you're choosing between A levels and IB) because I always wanted to study abroad at uni and thought it'd be a good preparation to study in English in high school, but apart from that, I think the curriculum is much more interesting and I really liked the fact that you could study different subjects (like Biology and Geo or something), cause in our local programme there are only strict combinations of subjects and you can't really mix them, and finally I actually really liked my IAs and EE, found the whole process very interesting, although ofc again I was (and still am haha) complaining while finishing them, but it was nice in the process I guess
when it comes to Biology and Chemistry, they're definitely manageable, from what I know of GCSE curriculum (and I studied from GCSE resources for BMAT this year), they aren't that harder in my opinion, ofc much extended and there are probably some topics that you haven't studied at GCSE, but, well, I don't think they are particularly high - ofc it also depends on person really cause when I started revision now, I realised I don't remember some things from the earlier Chemistry and Bio topics, but again, it's quite natural I guess, since it's a lot of content and revising it isn't that hard in terms of content, more maybe because there are many subjects, so again that depends what your goal would be, I'd say cause there are some people in my class who want to study in Poland at uni where only some subjects are taken into account - so e.g. if they're going to medicine, then they focus on Bio and Chem, a bit on Maths, Polish and English (since they also count towards the 'score' for the uni, but to a smaller extent) and kinda ignore their group 3 subject because it doesn't really matter for them (apart from passing ofc haha)
as for the tips, I'd say actually study throughout these 2 years because honestly I kinda ignored Chemistry and even more Biology in the first year and first term this year, kind of because of the pandemic and how it looked like and also because I focused on Maths as I was struggling with that, and although I did have good grades in both, I have to spend more time on reivision now cause, as I said, I don't remember some of the things/topics.concepts etc. on top of that, try to choose an interesting (or at least easy) topic for your IAs (and that goes for all subjects tbh) so that you'll find it more interesting to write them haha and if you can try to at least start working on them in summer between Y1 and Y2, I did my experiments for Biology and Chemistry IAs in summer and calculated a huge amount of my Maths IA and this was a really good decision (in fact, looking in retrospect, I should have done even more during summer holidays, but yeah)
as for the last question, I was planning to study medicine, I even have two interviews in the following weeks (in the UK), but due to brexit, even if I get in, I probably won't be able to go there (due to the higher fees), I just wanted to challenge myself and not regret not applying later on and I also applied to the Netherlands for medicine (cause as I said, apart from the fact that Polish unis aren't of the best quality, I really just wanted to study abroad for the experience I guess) and I'm also applying to some liberal arts and sciences programmes in the Netherlands where, if I don't go to the medicine programme (or don't get in), I will be able to do a pre-med (and then Master's in medicine) and something else alongside this (or only something else if that's what I decide) as I'm now not that sure if I wanna be a doctor in the end.. but yeah, the main and initial idea was medicine
hope it helps! if you have any more questions, let me know
EDIT: I just read what becausethenight said above and I think I kinda agree with this - UCAT and BMAT are a lot of work imo and even though I managed to get quite a good UCAT score (2750 B2) which was enough for an interview at Glasgow and Barts (and I'm international so the cutoffs and everything are higher than for UK students) and I don't think IB impacted UCAT at all as I took it at the very beginning of IBY2 (literally the first day ahah) so the last 2-3 weeks of August, I could focus on this only BUT
I got a very low score in BMAT (at least for what I was hoping for) and I think it was partially because I took this in November and had many IAs and EE deadlines in this time so I feel like I couldn't revise enough, but then I applied to Imperial and Oxford (ahahah) so, at least for Oxford, I would still have a very low chance of getting an interview even if my score was like 3-4 points higher since it's soo hard for internationals to get there, so it's not like I regret it in any way or anything (especially since I would probably still not get the required score, at least for Oxford, as an international even if I didn't have the deadlines and stuff), but yeah, you might consider that as well while choosing