Past papers are on the BMAT website, also check student room threads, sometimes they have links to useful practice questions. regarding the science section, buy yourself some GCSE textbooks second hand for all 3 of the sciences and read up on those. if you studied beyond that level, read up on that as well. Regarding the third section, just practice practice practice essays, look up essay questions for BMAT, do extra reading, read the news on healthcare just so you have a lot to say.