Thanks very much for the excelent info, everyone !

The prize my girfriend won is a £3000 holiday voucher which can only be used at certain travel companies. We can go anywhere in the World, but have friends in NZ and planned to go there in the next 2-3 years anyway so thought that this could be an ideal time to do it.

I have looked at our expenditure and estimate that we could get 100,000 BA Miles in around 9 months using a lot of the tips that Raffles shared. Unfortunately, the holiday voucher is only valid for 12 months so by the time we have the 100,000 miles, we'd have a maximum of 3 months to get flights which as you suggest we'd be unlikely to find in time. If only I'd found this site last year

Perhaps we'll use the holiday voucher on another trip this year, then if we rack up the BA Miles as planned, perhaps we can go to NZ as planned in 2-3 years, but do it in style (at least as far as Sydney!)

Thanks again everyone