He must have friends at school and you must know their parents a bit? What do they do? They might be able to offer a sleepover event so he gets to play with his friend and you go out without worrying about when to get back. You return the favour another time. There must be other single parents, maybe advertise a group for mutual support through the school newsletter? Speak to the school.
I do not have any family nearby and my little girl is slightly autistic. I joined a baby group before I went back to work and they kept In contact with me. The lady who ran the creche at the centre which is linked to church occasionally comes over to.baby sit . When I was really sick last month from a virus she came and stayed and took charge of my 4 year old. She didn’t take any money because she said I was ill. So there are genuine people out there. This lady is going to pick my daughter up when she starts reception in Sept so it does not affect my job