Airquiz
For revision, I used Airquiz throughout my PPL exams in conjunction with the PPL Confuser. I found that generally, the Airquiz exams were a bit harder than the actual PPL exams.
But what I would say is that I found a lot of the questions in the PPL exams to be very general to the extent that they were vague or ambiguous. So you do need to have a very good understanding of the course material to work out exactly what was being asked for in some instances.
If you haven't already got a copy of the PPL Confuser, I would recommend that you get yourself a copy. The Airquiz questions are very black and white where as the Confuser will give you questions in a similar format to the PPL exams.
Good luck with your exams!