As a general rule you want to be consuming 60-80 grams of carbohydrates an hour. You can be creative with what you bring on your ride. Natural is always better such as honey sandwiches or dried figs, but more often than not convenience plays a greater factor so sports bars, gels and drinks are your best way to eat on the bike. Doing the math before you get on your bike always pays off. Again, it is during training that you want to find what works best for you. People react very differently to the same things. Gels are great for some and cause stomach upset in others.
The rest stops on the tour will provide everything you need but it is a good idea to stock your own just in case.