Ok, I'm in year 13, and here is some incredible, insane advise:
for biology, watch Miss Estruch on YouTube. (she is the GOAT) better than all of my teachers and teaches topics in no time giving me those juicy A*s
Summarise her videos into flashcards and then use the technique of blurting to test your knowledge.
Geography is weird. Its easy and hard at the same time, as like half of it is common sense, but there are so many freaking case study's and facts that you need to know to back up your points, that it just makes it so hard to revise. Also, the NEA nearly killed me so good luck!
don't over revise. when revising for exams, start far in advance and just do a couple of hours every day using the Pomodoro technique and you will be dreams.