Hiya Pickle!
Working and juggling children and childcare is always a pain. I'm not sure how old your children are, but this would be my quick guide:
Ask school about wrap around care
Look at nurseries near where you live and near work.
Speak to your employer. Explain your situation and ask them for their help at this difficult time. Ask if you can do more flexible hours (10-2 M-F - 20 hours) or if you can do any work from home.
Try to rely on proper childcare rather than friends/family/exH as they can let you down or make you feel like a burden, although if you were going to job hunt for something (anything) closer to home, it might be an OK short-term solution.
Also speak to your local job centre. They will have a lone parent advisor who will be able to advise you of the options available. As a lone parent, depending on your income, you will be able to get a percentage of childcare fees paid through Working Tax Credits which makes wrap around care more affordable.
If you love your job and don't want to leave, you could also consider moving closer to work?
Compared to being on benefits, you are definitely better off financially if you work - although if you have young children, you may be able to be a SAHM and receive Income Support until they are 3/5 (legislation is changing) - which again might be something that you might want to discuss with the Job Centre.
I hope that you manage to get things sorted out when he is away next week - it must be very difficult trying to escape with 3 children!
If housing is an issue, there are often half way houses for homeless people and the ones near me always have families in them. You can stay until you find somewhere permanent to live and you also get priority housing though the local council schemes.
GOOD LUCK.
Seza