Potentially a friend's 19 year old daughter will look after my school age children for a short period whilst I work this summer. My children are aged 12, 8 and 5. The 12 year old doesn't really need someone but the younger two do.
She would be in my house and I may or may not WFH (probably easier not to in many ways). I would provide all meals and probably spending a bit of ice cream money. I would encourage her to take them to the local park/ cafe but otherwise play at home or in the garden.
She doesn't have any childcare qualifications but I have known this girl for many years and she is very sensible. She is off to university in September and wants to save up a bit.
What is a fair days pay though? If I put the younger two in day camp it would cost between £40-£60 (total) depending on the camp. But then I have the convenience of not having to take them and pick them up. Is £50 a day too little? I honestly don't know.