Marne, Its very sad that some parents don't teach their children though and worse still that in some cases, the parents' ignorance and prejudice is worse than the children's.
Its heartbreaking when this sort of thing is happening to your child and so frustrating that you can't be there to protect them. I really struggled when ds1 was being bullied. So many times I almost pulled him out of school, because I wanted to hold him close and keep him away from all the darkness in the world and I didn't feel like I could protect him (emotionally or physically). 
I do think that most schools do at least some work on it, in SEAL and PHSE, but sadly, this often this isn't enough to change the attitudes of some of the children, particularly the ones of the aformentioned parents.
Our ASD inclusion team offer to come into the school and work with classes to engender a better understanding and acceptance of SN. They are careful not to mention any children's names or single anyone out and as well as talking about specific SNs they discuss unusual behaviours and other 'differences' why they should be more tolerant of them and how they can go about it. I'm told it has been very successful in the past.
They are going to do this for ds. We can't tell him he has AS at the moment for various reasons, some of which aren't relevant here, but also because some of the language used to describe Autism is already used as an insult in the playground. He is incredibly talkative open and trusting and would be likely to tell the wrong person leading to him being bullied for it. Their coming into the school to do this programme won't change our decision not to tell him about his dx just yet, but hopefully it will help some of the other children in his class to be a bit more tolerant.
A similar thing was done last year for a looked after child who had had a very bad start in life and had lots of resultant behavioural problems. When he first started, the other children just wouldn't accept him and he actually became the focus of a lot of bad feeling.
Since doing the workshop, even though his name was never mentioned, he has become accepted and integrated well into the class. In fact he is one of the more popular boys this year. I presume the workshop was handled in a very sensitive way, so that the other children recognised some of his behaviours and actually stopped and thought about being more tolerant and understanding.
The other thing is the 'circle of friends' idea, where they carefully select a group of children, who then do some group sessions, which include the child who has SNs and they are encouraged to be good friends and support one another. They did this last year for a girl in my boys' school and its been really good. She went from an isolated little girl who spent all her time alone in the playground and was regularly picked on and bullied, to being part of a small group of friends who really seem to care about one another. I know her mum has been very impressed.
My ds is about to start this process as well, working one to one with his inclusion teacher in the first instance and then gradually introducing other children into the work until they have a nice cohesive group of friends.