lived in christchurch for 6 months few years back, nice place but it is small in terms of UK citys, hard to explain. I loved NZ as a whole and we are thinking of taking the leap in a few years, as i fell in love with the place.
the best way to explain NZ is its slightly larger than UK in terms of land mass believe it or not but the UK has 60 odd million people and NZ has 4!!
i stayed with a few kiwi families out there and the lifestyle is really laid back, your never too far from the sea, great winter sports lieftstyle
you really need to check about what jobs you can get, what skills you have.
the best advice is to try and get a long holiday over there to check it out.