The whole point though of working as a childminder is the flexibility it offers your own family. After taking off expenses (roughly a third of her income: insurance, resources, training, ICO fees, OFSTED fees, professional body fees, wear and tear, extra car insurance, extra car seats, playgroup fees, other activities) it's very likely that she's working for below minimum wage. She works hard for little income so that she can be at home for her children and take them to clubs. You could suggest that you send in a hot meal for her to warm up at lunchtime and then she does a pack up dinner on swimming days?
I only offer packed lunch type food and absorb that cost as part of my hourly rate. Food costs a fortune these days, so if people wanted dinner too on top of snacks and lunch, I'd be charging £2.50/child for dinner.
Holidays - I charge half fees for mine and half fees for theirs. The full fee for her holiday is a bit cheeky if she also charges full fee for your holiday.
It's common for term time only car to be charged at a higher hourly rate because many people can't afford to have no income for 3 months of the year.
For her child's sickness she is not allowed to accept mindees. She would be breaking the rules if she accepted your children into her home when her family is I'll unless it's a mild cold or something.
If you're unhappy, look elsewhere or hire a Nanny at a cost of approx £15/hour to include payroll, NI, TAX, plus sickness, hols and maternity leave.