Go for it. I am a LP studying Modern Language Studies with the OU. I have a fulltime job as a TA. I have one DS who was 4 when I started, now he's 7 and I am half way through. It can be challenging, especially as I have full time custody with no visitation (xh lives abroad and is broke all the time so also doesn't contribute a penny).
Studying is totally flexible. I find the best time to study is when DS is in bed, and at the weekend. I also do some studying at work during lunchtime when I get behind.
You will need some support with childcare on odd occasions, but if you can't make tutorials it isn't an issue. A lot of courses have a high level of on-line support, including on-line tutorials via something called Elluminate. On my current module I only had 2 obligatory attendance dates; my oral and written exams, plus a week's residential in Santiago de Compostela which was great. I am lucky to have the support of my parents, who had my DS for the week I was away. Other people who are unable to attend had an ALE; alternative learning experience.
I don't know what you are thinking of studying, but most courses don't even include a residential anyway.
As I have a low income, I also qualify for full financial aid, all my fees are paid and I receive about £240 a year towards costs, ie books. I was also able to benefit from another £260 towards a laptop.
My self esteem has benefitted immensly from this. Before, it was rock bottom after splitting from xh and becoming homeless and jobless.
My suggestion is go for it!