I worry about NZ's remoteness... both imports and exports have a long way to travel as do tourists... in contrast the UK is closer to major markets and its industrial capacity perhaps more dynamic than NZ.

But then I think about what's happening with the World and the emergence of India and China as both major economies and can see the value of being in a country within Australasia. I can also see value in a country that is perceived by many (China in particular) as neutral/independent and not following the USA at every turn.

Debt and Oil

This then leads me to my two greatest concerns over the future prosperity of the UK (and many other countries): Debt and Oil.

All of that money borrowed for mortgages or the flash car sitting on your neighbours' drive has to be repaid. The amount of debt in the UK is now simply unbelievable and servicing that debt will break many people. It is clear that the government will do what in can to artificially keep interest rates low - but as we have seen in recent weeks that has many unpleasant side effects particularly when other countries are increasing rates (e.g. USA) and consequently the pound comes under pressure and imports thus rise in cost which leads to... inflation... which leads to... the Bank of England having to raise interest rates... which leads to... you've guessed!.

Then we come to Oil which for me is the greatest concern of all. The recent price increases will undoubtedly hit western economies hard and give rise to inflationary pressures... but unfortunately these rises are not temporary and the only way is up... 'Peak Oil' is upon us and combined with increasing demand there is simply not going to be enough to go around. We have already started to see the big players position themselves for this and control over the World's oil is the number one game for the foreseeable future.

If even half the predictions of very eminent and sensible people come true we are in for a very rough ride indeed - and your thoughts then move to more basic concerns - such as survival.

Housing Market

I'll be honest - I'm budgeting for a potential return to the UK after 5 years - once we've gotten citizenship. Just in case things don't work out... BUT when you look at the long term picture I certainly do not think the UK will be better in 5 years time - far from it. In my more pessimistic moments I suspect that in 5-10 years from now I'll be glad I'm sat at the end of the world away from the turmoil, strife and conflict in a country that has sufficient resources to feed its people.

As I do not believe that house prices will increase in the UK over the next 5 years if I did need to go back I could slot straight in where I left off. However, if you expect house prices to fall (and I do) then I know I could go back far stronger than before.

There is a risk in being caught in any downturn in the NZ market... but you can work around this and limit your exposure (renting would help). I don't think property prices in NZ will increase much either... falling migration and the general economic downturn will sort that out.

Exchange Rate

{mosgoogle right}The kiwi dollar is higher than people would like. The core dilemma facing myself and many others is predicting which currency will fall furthest and fastest - right now it seems obvious that the Kiwi dollar will soften - and it has - but not against the pound. This is because the pound is weakening even faster... it is a choice of two evils: swapping for NZD now and hoping the dollar does not fall.. or keeping it in pounds and hoping sterling does not fall further.

And then we've come full circle. Low UK interest rates now mean a weak pound. Higher rates will of course prevent the £ from falling. The government need to decide what they would prefer: a weak pound combined with high inflation but low interest rates to stop the debt bubble from bursting rapidly OR higher interest rates to prevent inflation, dampen demand for debt and keep the pound up. As the Bank of England's primary economic mission is to keep inflation low... you can assume that interest rates will thus go up to keep the pound from falling too far...
I feel that if you wait too long for the pound to recover you might also find that it does so in conjunction with rising interest rates that will significantly increase the rate of decline in the property market. 

If you are relying on your UK house to fund your migration to NZ then you might want to sell up now in the knowledge that you'll not get any more for it if you wait. If you hang around too long whilst waiting for the currency to improve any improvement in the currency will probably be a drip in the ocean compared to a fall in the value of your own property brought on by those very same rates. This is assuming you can sell at all - which is often difficult once a market turns downwards.

Assuming you are cashed-up then you could take a view about which currency will give you the better return. I'm undecided - but the ability to get a 7% return on NZD deposits tilts it in my favour and I could use that extra interest to buy a currency option or offset the deposit on a forward contract that will lock in today's rate. i.e. convert your pounds to dollars today and then immediately enter in to a forward contract that will give you a similar rate on the 'return trip' so that you can convert those dollars back to pounds at the same rate in, say, two years time. Hence if it doesn't work out you can always get your money back.

Growth

I don't think the NZ economy is any more or less stable than that in the UK. Long term I have particular concerns over the impact oil prices will have on NZ - perhaps 5-10 years from now tourism might be in trouble? The prospect for agriculture looks good to me simply because of the population/wealth growth in all sorts of places, (China).
I read somewhere recently that China has pretty much used up all its arable land. Although the US is today the World's largest food exporter population growth trends dictate that within 20 years it wont export any food at all.. so perhaps a country the size of NZ with 4m people might not be such a bad place to live after all.

If NZ is successful in getting a free trade agreement with China (likely) then it could have major implications for business. The opportunities for export-focused people/businesses could be significant and this together with dramatic growth in China could tip the balance in NZ's favour.

Also if the US and China have a major falling out over oil (or any other resource in short supply - or Taiwan) then I would favour NZ by a country mile as you just know that the UK will fall behind the US...