Cheapest London to Sydney - NZ - London airline?

Anyone have any experience or thoughts on best deal I could get ?

Need to be in Sydney 13/10 for 3 days, NZ for 2 days then back to UK.

Try www.expedia.co.uk or www.travelocity.co.uk Both often have good deals and wuill search all the airlines. For best deals you need relatively little notice .e.g. today one way economy fare from
London-Oz £323 and a business class at £900 for travel in the next couple of weeks. Business class was gone later in the day. Obviously, the short notice makes it a gamble - if you wait on a cheap deal you might end up with no cheap seats left on the dates you want to travel.

Travelocity will search for the cheapest economy fare over several months. Doesn't pick up the very cheapest offers though. Expedia better for late deals.