Yes, I am from a state school and have done year 12. Regarding your options, Maths, chem, bio sounds much better than phy , chemistry, bio. It's because maths is strongly advised I guess with sciences and especially if you are taking physics, its a good idea to take maths along with it.
Now, if you are still unsure what to pick, pick ALL 4 of them and then drop 1 after a couple of months. Picking 4 A levels is a recommended pathway if you are not sure what you would like to study.
For revision, you should search as much content as you can online to help you. Yt channels, save my exams, pmt website and lots of other resources to look out.
My advice is to maintain CONSISTENCY. It's easy to study 5 hrs a day rather than studying 1 hour for 5 days. Please be consistent and just stay on top of your work. THIS IS HARD THOUGH.
I dont know about the schools you have mentioned