Unless you consider a cookie 'dinner', then eat in the lounge. Breakfast will be a smoothie, yoghurt, fruit and bacon roll. You can get a full English breakfast in Galleries Arrivals. First would have both dinner and a full breakfast, plus lighter options too.

They will have the Club kitchen -enough to keep you going if you miss dinner.

Don't listen to the ppl who say they'd turn down an F upgrade
If you've never travelled F, it's an experience. Sleep time in CW is more because of there being no dinner service.

So, to be clear- after takeoff they will do a cocktail service, followed by cookies and a hot chocolate

About 75-90 minutes out, breakfast will be offered.

Enjoy the trip!