Here is an older topic on the same subject from the forum:
http://www.pprune.org/private-flying...ions-exam.html
This is the first website that comes up when you type 'PPL Communications Exam' into google and will give you an example of the questions.
PPL Mania | PPL Training | Radiotelephony Exam
I personally used the transair/oxford aviation question/answer CD-Rom when I did my PPL writtens.