I would think very carefully about the move, I love your spontaneity, but PLEASE think carefully, this is a big move for your kids.
NZ is a wonderful, awesome country, I know, I grew up there and I love my country unconditionally BUT......I think you would be silly to move there on a whim.
Cost of living is very high, houses prices are though the roof compared to wages. IMHO you can achieve a better quality of life, but for that you need to earn a good wage, and a good quality of life does not always measure up to the standard of living in the UK (iyswim).
Housing quality is not as good as the UK, shopping is dire compared to the UK, choice is limited on lots of things (funnily enough people complain about only being able to buy seasonal produce!!!!), weather can be very variable, there are plenty of social problems in NZ including gangs especially in the North Island. New Zealand does not have all the bells and whistles that the UK has. Travelling is limited on low wages, even Australia, Fiji and Asia are out of reach for lots of families, that said there is lots of beautiful spots to go camping in the summer.
You really need to look at your finances, a lot of people would struggle to support three kids on one wage. Whilst the scenery can be amazing, you can't eat it. Imagine your lifestyle in the UK and have to do it on about 2/3 of the wage you currently have now.
Having said that there are lots of ways you can cut the cost of living, growing your own veg. Cooking from scratch is a cheap way to eat, there is far less processed foods i.e ready meals but still all the takeaway foods (of course), there is not as much pressure to keep up with the Jones' although there are still parts where the car, boat, house on the beach are important. I think food is better there (but again it is what I am used to), cafe food nicer but not the high end Michelin star restaurants you may get in the UK.
Nelson is known as quite bohemian, arty, nice if you can afford it. Packed out in summer but does have lovely weather. I would strongly advise you to look at employment options before going there.
Wellington and Auckland are probably the main areas to look at work in journalism. Auckland is very expensive but wages are higher, Wellington is indeed windy but also a lovely, compact city with a great cultural buzz to it.
New Zealand is parochial, quirky and does not suit everyone, you are not going to set the world of fire living there, but it can offer an amazing quality of life. I miss it terribly, but having grown up there I am used to the pitfalls. As someone who lives away from both sides of our families, don't underestimate the value of family support.
Also think of the cost of travelling back to the UK, $10,000 might cover 5 airfares, that is a big chunk of change.
I think you really need to look at your finances and then decide if it is doable. If it is then I would definitely give it a go but research, research, research and don't look through rose tinted glasses.
Sorry, I hope this didn't come across as a lecture!