You can get AMS-HKG-MEL for £1,744 per person in premium economy, travelling from 9-21 November. It's £600 more from London, or £200 more to fly back to London (I'd say the latter is definitely worth it).

That's a heck of a deal post-COVID and is quite straightforward.

I'd avoid transferring in Singapore because QF flies the two-class A330 SIN-MEL and so a large chunk of your flight will be in regular economy. Likewise, PER-MEL is on a 737.