More information would be helpful.
Are you on holiday?
Are you working, in which case how much do you need to pay for travel and childcare?
Or are you at home not working, and having a holiday at home?
In which case £20 a day is fine.
Alternative days out, with picnics, with days at home baking and doing craft.
See if any of her friends are around for a playdate for one or two days.
Go to the works and spend a tenner on paint and canvases for one day.
Spend a day baking bread rolls, cookies and brownies again about a tenner and then that's picnics for the rest of the week.
Swimming normally around a tenner for adult and child.
Not sure what the problem is, seems a normal sensible school holiday budget.
Unless you also have to buy school uniform or something out of it