I've really been enjoying your app as I didn't beforehand know that I liked doing crosswords! In the search for more UK-centric .puz files I came across the archive of Private Eye - unfortunately these all make the app crash:
Thanks for the comment. I believe this is a bug where the 1st across word in the puzzle is not on the first row. Please send me an email at bwit@pobox.com and I'll send you a fixed version to test out.