Hi,
AFAIK Exam papers are never released from the CAA. Therefore there are no 'past papers'.
The advice I give my students is this...
Use Trevor Thom....read the chapters do the questions in the back as you go. Then when compete tackle the first 20 Q from the confuser...see how you go..OK? Keep going...try the next 20...If not then go back and re-read those chapters where you are failing confuser questions.
There is enough material to pass the PPL exams between these two references (substitute pratt for thom if you wish - pratt tends to be better in terms of diagrams these days and is perhaps slightly lighter in tone).
Hope this helps,
FF