Hi Anna,
I feel for you as your kids sound young.
Mine are older and can be left for an hour or two as the eldest is almost 18 and she will stay in if I go out, you know, when I go to meet friends!!!
Where are you living? I very much doubt your near me, but if you were, I would be happy to help you out. I don't think you are though.
I don't know really what to suggest to you. A local teenager, a responsible one that is, that needs a bit of college boosing cash perhaps?
A lot of students will babysit for you and contrary to what people think, the vast majority of teenagers are lovely with kids and responsible!
Try contacting a college close to you - those on a childcare course perhaps would do this? You could even help them out in a few years with a reference?
If they are on a childcare course they have to be vetted by the police, even if they are 17, my eldest is on one and she had to have a police report done so you will know you don't have some ass in your house at least if you go this route.
Give it a try, you don't know, you might come up lucky.
Good luck.
Jo