Thank you for all the replies.

I have thought about all this and it is driving me mad. I have got to a point in my thinking at the mo of just jacking in the job and resigning.

This is my thinking >>> The Head Teacher knew that I was using the teaching assistant job for my training to become a clinical psychologist. When you are training you have to find somewhere in the system to work, so I chose the education system. Most trainees work in the NHS but I chose to do it differently. So the Head Teacher is not oblivious to what I was doing. I also gave him my cert in January and showed him my letter of acceptance but still nothing was done back then. I'm not someone who shouts about their achievements so I have just carried on as I am.

Also, I really don't think the school needs a clinical psychologist so I think I'm going to have to move on.