How to go back and study A levels?

I graduated sixth form back in 2021, i spent the last 3 years working and i want to go to uni but i dont have the alevels for course i want to do now I have an idea of the future i want.
I'd like to re-study an A level (biology) and take the exams next year (may/june 2025)
i just dont know how! there's 3rd party sites but sometimes they charge close to 2000! I was just hoping for some advice on:
- how to enrol myself for an a-level (preferably self-taught, dont want to join a school)
- if there's a deadline (i wanna take my exams next academic year)
- Whats the most cost-effective method
also biology has practical elements, how does that work or if a course has coursework (im also looking at geography)
if anyone could help i'd super appreciate!

Hi i wanted to resit my alevels for 2024 but soon refunded them as it was not my path for vet med- i decided to do a learn direct course for vet medicine which ended up being a similar price and is all course work, when applying to resit my alevels i went through a private school in Bradford, however you may be able to resit your alevels through your past college, my college unfortunately didnt let me but you can call and ask, i paid £360 for 1 alevel which included everything. this was self taught- i received no help from any college. I believe i applied in november 2023 to sit them in 2024 so i assume for yourself it would open in november 2024 to sit them in 2025. I would apply as soon as possible as places get taken quite easily. In your instance i would look into other routes as i found being self taught quite difficult but every person is different.