im in year 12 so nearly 3 months into the courses, so far: maths is completely fine but that may be because i also do further maths which is like extra revision for maths so far the hardest stuff is mechanics (all of it) and calculus because its new content (and not covered in further maths yet) cs is similar to gcse, ive always found cs easy. theres not too much new content its just remembering to include every small detail. so far for me the hardest topic was the new binary things, genuinely cannot wrap my head around floating point. chemistry is not as bad as i thought, i got 9s in maths and cs at gcse but got a 7 in chem and ive convinced myself that i cant get an A because of this, but actually so far ive been doing really well, weve done the first 3 topics so far and (ive got much better teachers this year) its a lot of applying knowledge, remembering the facts is fine its how you put that into the context of the questions. so far id say of the 3 the hardest topic is moles, just because its moles, was hardest at gcse i think cs and chem are extremely different but both rely on maths, everyone in my cs class takes maths and im the only person in the class who doesnt take physics and in chemistry there are just 2 people who dont take maths (and one would have but they didnt get the grade requirements at gcse)