Hey, Roz! Welcome to our shores - there are plenty of expat brits around, myself included!
Where abouts are you based in Auckland? Most of the dive shops run their own dive clubs, so you can "do the rounds" and see which, if any, fit what you are looking for.
I help organise a pseudo-club in Auckland, which is really a bunch of people who enjoy going diving together. We've got our monthly social coming up this Thursday - we meet in a bar called the Abbey in Greenlane from around 6.30pm. We've got about 20-30 regulars who come out diving, and about half a dozen of those are expat poms. If you want, drop me an email (andy AT www DOT techdivenz DOT com and I'll put you on our mailing list, you'll get info about all of our upcoming trips and the like. We've got a range of divers, from people like yourself through to cave divers and other techies - but they don't bite!
If you are after non-shop affiliated clubs, there are only three that I am aware of - the Botany Bottom Scratchers (
http://www.bbsdivers.co.nz), the Auckland Uni Club (
http://akunidive.com) though there are quite a few non-student members and the SODS (
http://www.sods.co.nz).
You'll probably find that there aren't that many Auckland based divers active on Scubaboard - try having a look at this local forum instead:
www.scubadive.net.nz