Chemistry, IMO, is the hardest subject you can do. The workload is tremendous, I have had to put more work into it than my other subjects, if you don't enjoy it I wouldn't take it on because, some of the topics can be quite tedious and boring, but others are really enjoyable to learn. I think overall, it's a good subject. It's so rewarding as well for the work you out into it, and the practicals are deadly
it it is hard, but worth it in the end.
At AS you will go over the basics, a2 is more in depth and explains AS a lot better. You'll be doing inorganic like transition metals, electrode potentials, redox (which is nothing like GCSE) and organic like amino acids, alcohols, amides etc. hopefully you'll get to do practical work like preparation of chrome alum, potassium dichromate and methyl benzene. You will be doing titrations and deductions which is interesting.
It varies for everyone, I didn't really understand a lot of things until A2. Also, ere will be calculations which can be easy and difficult.
But a nice subject to do
sorry that was very long winded!