Jez,
When you go to New Zealand check out an Aero club at Queenstown Airport (South Island) called Wakatipu Aero Club.
(
www.flying.co.nz ).
They have very reasonable prices for a C172 - 2 years ago they were about 1/2 of the price of a C172 here in Ireland at that time. Just walked into the club and was able to go flying immediately without pre-booking.
I did a couple of hours Mountain Flying with this club and I can safely say it was the biggest rush I have had in flying since my solo flight - great scenery, great experience - hope to return next year.
Enjoy your holiday,
Mixturelean.