How about volunteering at the school? Most schools can offer you a teacher assistant place and you even get a career out of it. My sister started this way and now is a Level 3 qualified nursery leader!
I am not single but I have just started working at the local hospital through their own temp agency (NHS professionals, admin & clerical bank) after being at home for 7 years. I am doing 9.30-2.30, mon-fri, term time only. The pay is rubbish but they are really flexible. I've been told I might not get the best jobs because of needing the holidays off but the rate of pay is standard whether you are using your brain or not! Having said that I started in the HR dept and it's really interesting.
Teaching assistants jobs are very hard to come by and schools tend to take on qualified staff these days. Volunteers have to be CRB checked to do it - they have to be very careful about who they employ
I used to be a single parent with a child at school and I took in ironing for extra cash.
Why not try going back to school to get a teaching assis qualification? It only takes a year and you would probably get funded as a mature student