I think its fair to say we kind of presumed, when you said Sleeper Service.

Personally, for a "holiday" flight, I prefer to avoid Sleeper Service flights as I'm usually in no rush to go to sleep on board, and prefer to eat when I fancy on the plane, and maybe watch a movie on board etc, without the whole cabin being plunged into darkness as quick as possible.

Having said that, as you plan on eating before the airport / plane, it probably doesn't really matter.

Although I do find the 'Raid the Larder' feature of CW is better outbound from LHR than it is inbound - or maybe I just prefer the UK selection of treats as I recognise the brands etc...