If you go to New Zealand, you'll have to deal with the shithead billionaires there who will have moved there a few days ahead of you, (since they'll get extra warning of course), who will have moved already into the fortress-bunkers they've been making for a decade or so there.
It should be a life mission of anyone in New Zealand, when the time comes, to find out where their air systems reach the surface and throw a few grenades down the ducts. For the good of humanity (whatever's left).
I think the billionaires probably have given it a bit of forethought. On the positive side they're an English speaking nation, and my Spanish is mid at best.