This has been discussed at length before matey and the general consensus is the confuser is a must . I used it for PPL and found it invaluable . If you can answer the questions in the confuser you will ace the exam. It shows you where you are weak and where you need to concentrate your efforts . It is no substitute for knowing your stuff , So use it in conjunction with the thom or pratt books .These are a personal choice have a look at both and see what suits
Good Luck