I got a grade 9 in all sciences at GCSE. I would say the CGP books are great to explain concepts you’re finding hard to understand - but don’t always cover every single thing you need to know if I remember correctly. Also sometimes doesn’t use the keywords your exam board looks for.
I would recommend making flashcards/posters/however you revise using: -the spec -your textbook -cgp book
Also websites like PMT and ‘Save my exams’ can help.