Hi,
I know how difficult it can be to arrange childcare with learning on courses so one idea I have for you to start with is to use the internet. The BBC do some online exercises to improve reading, writing, spelling and grammar in English so you could give that a try. I don't know if you have access to internet at home or how old your children are and whether they can come with you to an internet cafe but at least this is an idea:

http://www.bbc.co.uk/skillswise/

Good luck!