Good luck finding an itinerary from ARN-Australia on one leg
The best business class product from ARN-Australia would be Singapore but you will not find any award availability if you're not redeeming Krisflyer (Singapore's FF program) miles.
The best business class product that you could find space is Thai to BKK then SYD but they don't have full-flat C products except on their 77W. I believe Thai only flies the 744 to SYD from BKK which means it's not a full-flat bed so you would have to hope for a 77W from the EU to BKK. If Swiss has space from ZRH-BKK then I would do that instead of Thai Business the whole way..
Too bad NZ doesn't open up C space on their LHR-HKG-AKL route that often...