In reply to mintcake:
We did that - and were fine
The standard of regular campsites in NZ is very high - most have kitchens you can use that are equipped with microwaves, toasters cookers and even BBQ's. There is often a reading or TV room, and of course showeres and laundry facilites.
We never booked, and were fine (we did 10 weeks of camping) -
THe DOC campsites are much more basic and you will generally have to take your rubbish away with you. (they are very cheap)
Its good to mix between the 2, do a few days basic - then go to the luxuary of a 'top 10' site to swim, and do all your washing.