Anything up to 30 miles I tend to take 2 water bottles, one filled with water, the other with squash/high 5/something similar. And if it's first thing in the morning, it will be on an empty stomach, with a cereal bar and a gel in case I find my energy lacking partway through the ride. Between 30 and 50, a cafe stop will be built in. I carry the above, but will generally have a coffee and some sort of snack (flap jack, croissant, maybe eggs on toast or a bagel). Over 50 miles, I'll add another cereal bar and gel into the mix, maybe some jelly babies or similar, and the cafe stop now becomes a lunch stop and I'll have a sandwich, maybe eggs on toast with a side of hash brown/something potato-ish, sausage roll or the like. It seems to keep me going.