OCR
OCR means Oxford and Cambridge RSA Examinations. The professors that make OCR QPs are the same as CIE, so use OCR to revise. That will help u quite a lot.
For people stufying Edexcel, use AQA, they are the closest thing u will find. Infact, AQA is good for all, because its topic are made much shorter and categorised.
Hope this helps.
The Dude 321