Hello pointybird.
You may wish to consider taking out a credit card. Credit card providers invariably offer new customers 0% interest for one year on new purchases. As long as you can afford the minimum payment, then you can spread the cost of your flight without paying the banks a bean!
Try this site out:
http://www6.marksandspencer.com/pages/default. asp?PageId=home&Product=CC
I have an account with Marks and Spencer and have always found them to be very good.
We went to New Zealand last year. We visited Auckland, Wellington, Rotarua, Christchurch and the Southern Alps. It is a truly beautiful country and well worthy of the exhausting and long journey. I really do hope that you make it and experience what we thought was a truly magical country.
Good luck!!
Scott