Until December 2004 I was a history teacher. I left to work in industry, but I am considering returning. I enjoyed teaching but found it stressful.

Is there an organisation that could help me deal with this and the anger as the tiredness sets in?

You don’t tell us why you are considering returning to teaching. Is this a positive decision or because you cannot find work in industry? Do not think about returning unless you can say it is for positive reasons, otherwise you will only quit again. There is a teacher support line, but if you need it before you return, this supports my view that teaching may not be the career for you.