I clearly recall this thread from back in February.
I found the same difficulty as the OP, and was unable to work at all whilst my children were in primary school (hours didn't suit, nor did holidays, couldn't afford wraparound childcare, the list goes on).
When you have very young children people always talk about how it will be so much easier for you to get back to work when they start school. Errrm, no! It isn't. Not unless you work in a school, and jobs like that are like gold dust around here.
There are still far too few employers who are flexible enough. We need a lot more term time only contracts, with the facility to work from home when necessary. Working from home is a much more realistic proposition now with the explosion of the internet, broadband and wifi than it ever used to be. I know. I work now and can work from home if necessary, but it took me years to find anything and my youngest is now 13.
OP has always had my sympathy here. In fact, it really irritates me to think that there must be a large amount of wasted talent at the school gates. Women (and sometimes men) who have a lot to offer to a workplace and who would like to work, but who can't for reasons to do with childcare, school hours, school holidays etc. When I was a SAHM I knew a lot of them. We have almost all now drifted back into some paid employment now that our kids are of secondary school age and can virtually look after themselves. It was hard though. Very hard, disillusioning and demoralising too.
Keep pegging away OP and others like her. The job market is improving somewhat now I think, so something might come along when you least expect it.