I feel desperate over a levels

so basically last year for AS, I got ADU. I did so bad but I wasn't surprised at all because my attendance was 50% I didn't do any work at all, so this year I've turned things round and I have been getting straight A's. The thing is with religious studies, I got a U last year and I really don't know how to revise for it. At school, we had like 5 different teachers last year and this year we have 2 completely new ones who don't even have a degree within religious studies, I'm scared I'm going to fail, I need at least a C in the subject, it's actually a shocker how I'm passing psychology but not religious studies/philosophy and ethics.
What do I do?????? I'm so sad
I'm really dissappointed in myself because I get A*A* and then an E or U how do I get it up to a B at least?