I can't really add to what everyone else has said, but in my opinion you should keep it as you have already done half a year and it seems a bit of a waste to drop it at this stage. But if you're really not enjoying it then maybe you should drop it because it might have an effect on your other grades.
Last year I hated Chemistry and could never motivate myself to revise for it, and it reflects in my grade. But I am taking it again this year because I need an A in it for one of my university choices.
I am getting worried about what everyone is saying about having to get an A in AH to better an A in Higher? Surely a C in AH is better than an A in Higher? For Higher Maths last year I got an A but this year I am aiming for a C or maybe a B in AH. I agree with what Daniel said about one to one teaching. I am the only one in Maths and it's great!
When can you expect yours?