If I am going to be honest, I hardly revised, I did my GCSE's in 2019. I didnt actually revise properly until like 2 weeks before bc im so lazy, I am just saying to prepare early, because if you want to do well in A level you should start practising now.
GCSE is not hard to cram last minute, so you should be OKAY, just be effective with your revision, i.e look at exam walkthroughs on youtube.
I got 6s and 7s and 5s on my mock but on the actual exam i got 9s,8s and 7s. Guess im lucky lol