This is a dilemma...I have some experience of some English schools now, they used to be very good and many still are I am guessing you are in a poorer area , is ther anyway you can move perhaps into a more rural area, my daughetr lives in the UK and she has had great schooling.but they do not live in any big town .Bullying does go on a lot, and I think you have to speak severely to the school head master /mistress or someone in charge its their responsibility whilst the children are in school, I dont think you will get anywhere speaking to parents ..again you may have to move .if it were me I would be hi tailing it out of there to a better area ..children have got an upper hand in UK due to big government rules ,...good luck let us know how he is doing ..