I found the BGSonline questions bank (Bristol Groundschools) very useful .
Its got a great selections of questions, and the answer explanations are very clear and easy to understand on some of the more challenging subjects.
What I found most useful, is the way their Q Bank informs you of the questions you are getting incorrect, and identifies which area of the subject you find most challenging using the analysis section of their test feedback page. I found this useful in structuring my revision on the parts of the topic I was weaker at which makes the whole revision process much more efficient.
With regard to the new material, I found Bristol have been very good at generating new question based on feedback from their students. This is very helpful in helping you prepare for potential new questions that appear in the exams.
But I agree with previous posts, I found the BGS online an excellent Q bank when use as a revision tool, and its great value for money too.