Regardless of study manuals or CBTs, to get you ready for the actual exam, ie to help you focus on the areas required for the exam and the question styles, get the PPL confuser, and also take a look at
www.airquiz.com. You can sign up for individual exams @ £3 each, and can generate as many test exams as you like.
It is helping me convert the book theory into the knowledge tested for on the exams!
Mark