Preflight dining doesn't disqualify you from eating inflight (amusing image of cabin crew checking your teeth for traces of bacon butties here ). I'd snack in the lounge and then dine on board; the flight doesn't leaves too late (I presume you're on the 2035) - you'd probably be bedding down at 2300-2330 after the meal service with around five hours left to go of the flight so a fair amount of time to sleep.