Hello i need some help with an awards booking in terms of any availability.

I am a BA gold card holder, have 450K avios and 2 x Amex 2 for 1 vouchers and am trying to find a routing in a premium cabin LHR to Melbourne for 4 x people. 23-29th Dec returning 9-13 Jan.

BA are showing zero availability to anywhere close during this period, closest i could get was Tokyo but there we no connecting flights to Australia.

Does anyone have any ideas?