I'm a regular on BA7. Best advice is no sleep the night before, then get as much sleep as possible on board after the meal service.

In CW the first meal (Lunch) can be a bit slow and ends about 2 hours after take off. Breakfast is served around 5:30 am (2 hours before landing).

I tend to binge on food in the lounge beforehand and go straight to sleep, topping up on food in the club kitchen.