I do History, Law and English Lit at A2. Tbh, it's gonna be a stretch to get your grades up. I find mocks to be somewhat accurate in summing up where you are.
If you haven't already try to do some past papers and pay close attention to mark schemes. It's not just about having knowledge of a subject, but also recognizing what a question is asking for and presenting it to examiners the way they want it.