You are looing for the cheapest fare available and you do not mind perfect routing or you see advantage of long layovers have a look on another awesome deal from Europe to Australia or New Zealand based on Air China. (Star Alliance). Return flights are available already for €492 incl. all fees and checked bag. Look for flights departing from main airports in Germany (Dusseldorf, Munich, Frankfurt). You can choose to fly to Brisbane, Melbourne, Sydney or Auckland. In some cases you will be eligitly to get free transit hotel in Beijing. (More details here).
If interested in this offer with Air China you will find the cheapest flights in May and beginning of June 2018. Max stay 3 months. Promotion is running till 28th of February..below you can refer to our booking sample on each of possible routes.
UK – Perth, Australia from £516 (Etihad Airways)
Booking sample of Cheap return flights from Germany to Australia or New Zealand from €492! As in aour above link your outbound flight from dusseldorf to Melbourne would be on 13th of May. You would return from Australia back to Europe on 27th of May 2018.