I took GCSE's two years ago now. I don't really understand the numbers too much, but here is some advice for you.
Biggest tip. Don't revise too much. By that I mean excessive. Your brain will soak things in at the start of a revision session because it's a new bit of learning, and at the end because it's the last bit of learning you have done. Break your time up into 30-60 minute blocks maybe once or twice a day. No more.
Also, spread out your revision over subjects. Don't do one subject all at once, because you'll get burnt out. And you don't want to get burnt out.
Finally, if you are struggling structuring answers, take an example question to your teacher and ask them to go through how they would answer it. They know best.
Good luck! Nothing is impossible, trust me!