Could you specify what exactly you are having trouble with? I did TKAMB and Triple Science, so maybe a few others and I could help, but you're not giving us much to work with!
For TKAMB - go on sparknotes, helped me through TKAMB and AS, still using it for A2.
Triple Science - the textbooks are pretty helpful, well AQA ones were, it was all broken down. Just make sure you know the key points and you should get an A. A lot of GCSE is just regurgitating facts back at them.