Get the Confuser!
The AFE Q&A simplifier isn't bad, but the PPL confuser is invaluable IMHO.
I read the AFE Met book, subscribed to AirQuiz and used the Q&A simplifier and thought I was ready for the paper. Then I had a look at the Confuser and realised I was not ready at all. The folks at the CAA have a wicked sense of humour when it comes to writing questions!
Good luck.