A couple of hours sleep in an A330 prior to the flight would be great, and this would be achievable in business class, however, given our fantastic staff travel system, your most likely to be in cattle class and unable to sleep.
Regarding turning up for a long haul flight not rested, I found the best way to do the late evening Asia to Euroupe departures was to not sleep prior to flight. So you have been awake about 15 hours prior to the flight. The other crew would have generally slept prior to flight. I felt quite alert for take-off and climb, but then had no problems sleeping for about 6 hours, i'd return to the flight deck over Afghanistan, where the other pilot would then have no problems sleeping for the next 6 hours and returing totally refreshed for landing.