I'm doing Chemistry, Physics, Biology, Maths and Further Maths. (I'll probably drop biology as I've decided not to go into medicine)
I self studied a lot of A Level Chemistry over years 9-11 so it's been quite straightforward so far, but there wasn't much of a step up from GCSE so most people who hadn't self studied probably wouldn't find it too difficult at the moment.
For Physics a lot of time was spent going over basic skills, uncertainties etc, and then mechanics which has been okay so far.
Biology has been a bit of a content overload, lots of memorisation
Maths has been quite intensive because people who do Further Maths at my school do the whole Maths A level in year 12 so it's been going quite quickly, but we haven't started Further Maths content yet.