with difficulty.....

Started at airline network - www.airnet.co.uk - it came up with loads of fares (ex-UK in Nov, return in Dec) for about £2100. No availability on outbound, plenty on return.

Couldn't find the fare rules and eventually found www.wefly.co.uk

This site has a great search engine - you can put the criteria in, search on 'fares' and it finds the fares. (for those BA lurkers, it even finds ex-TIP, ex-ATH fares etc)

For the NZ fare, on wefly it finds a 'Z' fare for £2135....(OK, not £2k but getting close)

Go to http://www.optimalmove.com/flyertalk/galileo.html to find appropriate itineraries in Z (typically NZ1 LHR-LAX then NZ5 LAX-AKL are the outbound sectors with availability - all the UK booking engines seem to default to NZ1 LAX-AKL which rarely has Z) and you should fnd an LHR-LAX-AKL-SYD-AKL-LAX-LHR itinerary all in Z you can book.

£2100 to OZ in Z (earning 45k status miles in some star alliance programs) seems reasonable to me. Especiallly in the new NZ Biz class. Their new Premium Economy product looks reasonable too.....