HI,
I have a Minder who comes to my House every day and looks after my small Children. It has worked out much better for us than when the kids were in creche. Best places to advertise are Gumtree, Mindme and Rollercoaster websites - not sure where you are based but you can put an ad up in some local shops too.
If you are only looking for termtime put this in the ad, there may be some minders who are studying parttime etc and don't want fulltime hours. As you are their employer you need to pay them at least minimum wage (€9.15 per hour) and also pay Employers PRSI (Employers pay 8.5% employer PRSI on weekly earnings up to €376. Employers pay 10.75% employer PRSI on weekly earnings over €376). You also need to deduct PRSI and USC from their salary.
We pay our Minder €11 per hour, I also pay her PRSI/USC contribution (don't have the heart to deduct it from her Salary).
Agree upfront what the T&C's are; e.g. if she is sick for a day do you pay her. Also as she is an employee she is entitled to Holiday pay. I agreed with my minder that she takes her main Holidays (2 week block) in July - same as us. Any other ah-hoc days (e.g. a Wedding, Long Weekend away) I pay her for the day. If she wanted to take e.g. 2 weeks in November I wouldn't pay her (this hasn't happened). I also pay her for Bank Holidays.
Also agree what level of housework you expect. My Minder cooks for the kids and tidies up their Toys etc, I don't expect her to clean the house.
Overall it does workout more expensive than having 2 kids in creche, between her salary and the extra spent on heating, food etc in the house. I also signed my older child up for more activities in the afternoons than creche.
Good Minders are hard to come by so you need to treat them well.
What you are describing might suit a mature Mother who has e.g. Teenagers and is happy to have Summer/Easter etc off