Not an AIBU but an update from a previous one (I'll link in comment below) -
This Thursday bully punched my son on the arm whilst in the dinner hall.
Friday morning I went in to speak with the HT. I explained that clearly watching this child during play times was not good enough as the child was then seeking opportunity to hurt my child at other times. HT checks who is on duty that lunch time and assures me that something will be done about this and that the child would be very closely watched that day and he would make sure my son had a good day and leave for half term on a good note (Half term a week later here in Wales).
Just after lunch time on Friday I get a phone call from a teacher saying there had been another incident. The bully had slapped my son around the face using both hands. She tried to play down the situation but I insisted I was coming to the school right away to bring my son home, I did not want him there one minute longer.
It transpires that what had happened is the HT had asked someone to bring bully to his office to speak with him about his actions the previous day. HT had to nip out of office for a short period and bully was to wait for him there. Teacher leaves bully there, bully then leaves the office. A teacher tells bully HT wants to speak with him and he says HT already has. He continues to the playground where he hits my son again.
HT really angry and is calling bullys parents in. He says he hopes my son will return after the holidays but I'm very apprehensive, ask if something will be in place immediately on the Monday they go back and he says yes. They will now keep the boys completely segregated but that my son won't be inconvenienced by whatever they put in place - it will be the other boy who is watched/kept from him not the other way around.
On the Monday he goes back I will speak with HT to find out exactly what is in place that morning before making the decision on if I should send my son back or not.
It transpires that bullys mum has been lying about trying to get her son help and in fact she denies there is anything wrong at all! Other mums have since told me some truly horrifying things about the impact this child has had on their own children. My own child is saying 'I don't want a life any more' 
I also had to miss a two hour lecture to collect my son and take him home. So what do I do? give up Uni and homeschool because of the bully? Do I contact the LEA now?