Working in a school

Hi. I really hope somebody can help me. I'm hoping to work as a TA in a school. As I must work more than 16hrs/week to stay off JSA does anybody know how many hours/wk this equates to when working in a school??

I think it might possibly be that I need work 22hrs/wk during school time.

I've tried looking on directgov website, but I can't find the answer.

If anybody knows for sure it would be handy.

Many thanks