As busyness said, it depends how much money you have to spend. If you're intending to come here as a 'better place to raise the kids' and are taking a pay hit to do it, chances are you're going to need to assimilate in with the rest of the kiwis and live in Auckland.
If you're not particularly bothered financially (and it's goddamn cheap to live here compared to the UK) you can pretty much go anywhere you like. I'd suggest somewhere close to Auckland but with rural coastline. My folks have a place on the cliffs at Maraetai beach. All the charm of a very small town, with the convenience of Auckland nearby.
Seeing as you're doing the second half of the "kiwi goes to the UK to earn big money then come back to cheap old
NZ to spend it" thing, I'd suggest following in their footsteps. While you're in the UK and have a much higher earning potential put aside as much as you can, as it'll go further here.