You could use YouTube videos to help you learn the concepts. Plus use a textbook and a revision guide and start making notes asap - things like mind-maps, flash-cards, write a summary of key ideas for each topic, etc. What I've done in the past for certain topics is I used one textbook to make notes from in the morning, and the revision guide to just read through the same topic in the evening. It really helps things to stick in my mind.
CGP make good textbooks and revision guides.
GetToKnowScience is a good Youtube channel for science videos. Also my-gcsescience if you want core-science videos.
Hope that helps.