I'm sorry if I came over as harsh but having re-read some posts, it looks as if this is an H problem.
Most families I know, have a summer holiday for 2 weeks and even if they can't afford to go away, it means there are 2 adults to do the day care of the children.
Why can't your husband take time off in the summer @allsummereverysummer ?
That would leave you with 3 days for 4 weeks on your own- 12 days.
Although my DH worked long hours and was away a lot, he did take holiday. sometimes I went away on my own to see friends for a few days or long-distance family.
I also used weekends to go out and do shopping alone, or have my hair done, have spa day, or whatever, leaving him in charge.
Do you not have a network of friends who your DCs can see or play with their children?
No family nearby to share the load?
Local Facebook sites are usually full of things going on for kids at museums, play centres, many arranged by the local councils.
Have you had a look for these?
I don't understand why your H isn't taking holiday so he can be around and you have a family holiday.