In England there is a move to reduce the size of snacks provided in dispensersin schools, as for pizzas, absolutely none on any school's lunch menu, as far as I know, & popping out for one, is unheard of amongst schools, in fact some ban pupils from leaving the premises at any time, unless it's an emergency, it does happen in some colleges, but as far as I know, not at the top ones like Eton [founded in 1440, fees £25000 a year] where a student could be expelled for doing it, a few others like Oxford & Cambridge probably would too, over here it is i considered a disgrace for the expelled pupil's family too.