Carlywurly, see, put in a sensible, non-goady way like that, I totally get where you're coming from. I appreciate that with little notice and a full time job things like this aren't easy.
HOWEVER, OP is banging on about how good teachers have it, when the vast majority of us know this not to be true. She's bemoaned their pay, their holidays and their lack of work stress. what a twat
Have you tried speaking to the school for the following year and explaining your situation? I do think it would be fair for them to give you a little more notice, wherever possible.