In reply to Cusco:
Mountain biking, I just use water, as easier to clean the bladder and we'll stop more often and I can eat then.
Road biking, I used the High5 Zero tabs for hydration (the neutral flavour is quite nice, actually - rather than the flavoured ones), or SIS Go Energy for very long rides.
Food is flapjack, banana, fruitcake, cereal bars, Marmite sandwich and so on - might treat myself to the High5 bars once in a while for a big event. Sausage rolls or cheese or ham sarnies are fine in winter, but in summer they go manky in the heat in your pocket - unless you buy en-route.
Incidentally, my dentist recommends a swill of mouthwash after a ride to neutralise all those sugary snacks.