Our school has banned first break snacks other than fruit or veg, since we have been there...8 years.
Dried fruit is also banned for first break snacks. After 2 years they introduced fresh fruit and veg for the lower school provided by the school, which was better, as they were in control then.
My feelings are that they can pull out the government guidelines on healthy snacks and lunches and use this to say they can regulate to what they deem appropriate for the children, just like making them wear appropriate school uniform.
It is a way of forcing parents to provide one of the five a day really isn't it, in the hope that if all the kids are doing the same the stubborn ones will oblige and eat some fruit. So look on it as an enhancement to the whole schools diet, rather than a restriction of your own child. I have to say, I do follow suit and munch an Apple or bag if mini carrots with them if I am helping out, which I would never do at home!
Homemade flap jack is a sheep in wolves clothing btw, or mine is any way...treacle, sugar, butter, processed oats...it is about as bad as you can get...and twice as yummy, and yes I do send it in their lunch boxes, or home made muffins, which is a ditto!