My-GCSEScience: Your school may already have it, but if they don't then there's a free version with 50 taster videos, or a paid version with a video on every topic in the spec (£24.95 for Combined, £49.95 for Triple Award). There's exam board specific ones for AQA, Edexcel and OCR Gateway
The CGP revision guides- they saved my life! Also the YouTube channel PrimroseKitten has loads of videos- I found the summary videos for an entire unit the most helpful, especially later on :-)