MLamont,
If you are intending to fly in NZ I think you have to convert roughly 5 hours flying time before they will let you go solo, so most of your flying will be with an Instructor. I can't remember what the requirement is, or what it is for but I think it is 5 hours.
If you purchase the first Module of the ATPL from one of the Ground schools, about £800, you could take them to NZ and study there but why ruin a holiday studying 3-4 hours a day - enjoy it! Also you may want to keep the £800 for travelling.
I went to NZ at 22 for 10 months came back completed my PPL and NR, now I'm starting my ATPL with BGS. I'm now 24.
I would take 8 months out relax, possibly fly a few hours in NZ, come back and then go for it.
Good Luck