It starts before school and that is where the Children and Surestart centers come into it. There is still a problem of the 'hard to reach' families (these are usually the ones who would benefit the most. This 'problem' can only be removed by good investment in the development workers in the centers, i know of many in the most disadvantaged areas who go out and try to persued parents to come to classes and enrole their children.
There does need to be a big change to what goes into food, as well and what is available to buy, although i have noticed that more small news agents have bananas and apples on sale, this should be encouraged via the tax system, so that they do not loose out by stoking fruit that does not sell.
I have been vegan on occassion, mostly vegaterian and in the past there have been areas that i have been working in that nothing was on sale that i could have ate, i tended to carry a tin of pineapple around, just in case.