Like others have said read the whole CTC selection threads. Don't be put off by the volume of information in it as you will have to trawl through as much, if not more information when you're doing the ATPL studies.
With regards to books there is a good preperation book I used. It's called 'Getaheadforthesky' It's a generic FTO / Airline selection book but has everything in there you should need. I also invested a speed mathematics book but only because it had a been a few years since I had done any mental arithmatic.
The chances are if you apply now you will probably end up on one of the CP's (if you pass selection) that would do all of their ATPL study in the UK before you come to NZ. At present the ATPL modules are taught at the same time as the 'learning to fly' bit so you're juggling between the two. Personally this is a nice balance and the thought of doing all 14 ATPL subjects, back home, in 6-10 months, before you even touch an aircraft would drive me to tears! But that's just me!
There will be a lot people that will advise you not to train now and everyone will have a very valid point. Whether for or against. You will simply have to decide yourself, based on the information you can gather whether now is really a good time or not.
Chilli.