Hi! I'm about to go into year 13 and I do biology and maths, both AQA
For biology I use senecalearning.com to cover any content that I don't quite understand/may have missed due to being off, and then I use physicsandmathstutor for exam questions. A huge part of biology is hitting the correct mark points because mark schemes can be soooo specific, so doing past paper questions and marking them again their markschemes really helps to make sure you're using the right keywords etc
For maths practice is KEY. You ideally want to do as many past paper questions as possible. As others on this thread have said, TL Maths is a really good resource and I find his videos on YouTube really helpful for when I don't understand a topic fully (mechanics, I'm talking about you). My school also uses Dr Frost Maths which has questions and linked videos, but I'm not sure if this is freely accessible without a school login