OK ... some living costs:
First, don't let anyone tell you that what you can buy for a pound you can buy for a dollar ... People seem to think that but it isn't true.
However, if you have pounds to spend things are generally cheaper than in the UK ... I bought a lovely lampshade in the shape of an aeroplane for DS' room for $50 thinking it was good value at 15 quid (good quality item etc). Now I have been here for 3 years $50 seems REALLY pricey for a child's lightshade!
I was speaking to a friend the other day who rents out properties and she said that $500 a week should get you a reasonable place in nice areas ... but not the top spots near the city.
Takapuna is a very nice part of Auckland ... gorgeous beaches etc. Like Chuffed says there are excellent schools there.
Children tend to start school ON their 5th birthday ... so if you are NZ by the time your DS turns 5 he will start school on his birthday of just after. If your DS birthday is the 20th September then that is the last week of Term 3. He could have a couple of days visiting then start properly at the beginning of Term 4 on the 10th October. This is a great time to start school as he will have a Term as a New Entrant and then the whole following year in Year 1.
Living costs: We spend between $200 and $300 a week on food ... about the same as we did in the UK BUT we eat much better ... that includes meat and wine every day In the UK we didn't eat that much meat as it was too expensive and we only drank wine at weekends! Fish is very expensive here as is organic food (I try to buy organic when I can).
Petrol is $1.24 a litre at the moment ... it was 95c a litre when we arrived 3 years ago so it has gone up considerably.
You can get a family car for maybe around $15,000+?? I think?? Of course, you can get cheaper. My friend is selling her 10 year old Land Rover for $10,000. Most cars are automatic. Japanese makes are the best value. European cars are expensive to fix.
Health ... if your DH's company offers health insurance take it. There is a health service but you still have to pay extra. Adults pay $40-$50 to see the GP ... children under 6 are free but if you end up in A&E it costs $20 for a child.
We have health insurance that covers hospital costs. We don't mind paying the GP as we don't go that often but it is good to have insurance in case you need an op to avoid waiting lists etc.
You won't feel like a square peg in a round hole. NZ is the most 'English' of places to emigrate to ... I never feel like I am in a foreign country. Auckland is a very multicultural city ... full of South Africans, Brits, Asian (Korean, Chinese, Japanese, Malaysian as well as Indian) I love the richness of the culture here. The Pacific Island culture and Maori culture are fantastic (although sadly, many white Kiwis might disagree).
I have gone on long enough ... but ask some more questions and I will come back to you!