Hi there,
I did A-level Edexcel Geography and i bought a revision guide not CGP so im not sure about your revision guide. But mine had one page summaries and it was definitely not enough information. Therefore, I made like quizlets based on information given in classes as well as using Seneca learning. So based on my experience, I would say just memorising a revision guide is not enough as you need to practice exam questions and learn a variety of case studies in brief not in detail.