Others have given you good advice. Unfortunately it seems that most vets don't know/don't care about good pet nutrition. For over a year of cat ownership, I thought dry food was healthier and thought wet food was more of a "treat" to be used as a supplement to a dry food diet. So you're not alone in being confused and misinformed about a healthy kitty diet.
I feed my kitties Wellness Core wet, which they love and it's available at just about every pet store I've been in in the States...not sure if it's available in New Zealand, but generally, wet food is pretty much always healthier than dry, and you want to avoid foods with grain in them.
Jennifer and the kitties, Coda and Caligula