Don't worry about energy bars or gels. At every water point you can get as many of these as you can carry. (I think it will be Powerbar, it was last year) As for drinks, you get fresh bottles at each water point. (Also Powerbar) If you want to use any other drinks, take refill sachets with and mix it with the water you get at the water points. If you want to use any other food on the cycle leg, carry it with you. On the run they also give coke, marmite samies, and baby boiled potatoes. If you want to drink or eat anything else, take it in your fuel belt.
