Back of the envelop:
A330 fuel burn 5600 kg/hr
A380 11500 kg/hr
Let's put our comparison hats on!
alliknowaviation.com
QF A330-200 234-271 pax A330-300 297 pax say 265 pax average... since I don't know your aircraft type.
A380 485 pax
- qantas website
Flight time SYD-HND 9.75 hours SYD-LHR 23 hours
that gives SYD-HND 206 kg per pax and SYD-LHR 545 kg per pax.
But what this is missing in this calculation is allowance for luggage, class of service and freight. Freight might be a big item if they factor in ratio of pax weight:freight weight. Based on the carbon ratios between the flights, the fuel per pax on SYD-LHR would have to be 84 kg, so only 15% of total fuel consumption attributed to pax.
hmm