Make sure you go with others over there as you're not very experienced. They will tell you what to look out for if you tell them you are new to the sport. Intro yourself via the NZ forums.
also have a quick look at
http://www.nzkiter.com/ maybe.
But to answer your question, there is this perfect flat water location south east of Christchurch. (quite close actually 10kms from the middle of chch) It an estuary between South Shore and Sumner. (real nice spot in summer. you'll love it.) Heaps of kiters there too. Have fun.