The required postage will depend upon the weight of the item being sent. Royal Mail have a chart showing the costs (See links below). New Zealand comes under the Rest Of The World column.
How many stamps are needed to send a letter from Texas to Alaska?
It takes three stamps to send a letter to Norway.
700 Stamps
3 stamps!
12 stamps
what the price to mail letter to
The number of stamps that you need to send a letter from Australia to London, will depend with the value of one stamp.
1.
One
300
1
about ten