Mine is a full English cooked breakfast (minus black pudding
) on the journey across the Solent. As most journeys are over an hour (further GP's are nearly 3hrs) which gives the stomach time to digest such food to a suitable level ready for the event.
I tend to keep some dried fruit/granola bars and some water/squash/flash of tea in my gun bag. If it looks like it will be hot then I freeze the squash the day before and then it is a nice and cool drink.