Hi Colin. Try some of the links below for whistle newsgroups (the links did work when I bookmarked them). Some are new and only building in size.Dale Whisleys is about the best.
http://members.aol.com/planetmac/whistle/whistle.html
http://clubs.yahoo.com/clubs/tinwhistlepage
http://forums.delphi.com/preview/main.asp?sigdir=tinwhistle
http://www.verinet.com/~ktcrumb/tunes/
http://www.mindspring.com/~whistler/tutor/index.html
Happy blowing
Mike