Starting media + didn’t do it at GCSE

I’m sorry I know this has probably been asked before but I couldn’t find it if it has.

I’m starting media studies (AQA) at A-level but didn’t do it at GCSE. My sixth form is attached to the high school I went to and the school did offer it at GCSE so I think most people doing it in sixth form will have done it before

Is there anything I should do to prepare or catch up? Will I be behind everyone else?

Any advice is appreciated :)