I can't speak much for Physics and Biology but Math should relatively be simple to self teach. All you really need is examsolutions.net; study the topics in the order they're presented in, don't move on until you fully understand a topic. Then do the exam questions (which are at the end). You can then use physicsandmathstutor,com for practice/past papers (there are also useful notes on there for math/physics/biology)..