It probably doesn't fit your business plan or rural location OP but just throwing this in here in case people are interested. In my local area (a London residential centre in Zone 3) there is a creche that is not affiliated to any other enterprise like a who or gym. They take kids for a minimum of one hour and a maximum of a whole day. Age range 3 months to 5 years.
You book in advance but some places are also reserved for walk-ins and they have a variety of pricing options such as buying blocks of hours or days in advance at a discount.
It's prefect for freelancers, people who only do occasional work, mothers doing KIT days at work, emergency care if normal childcare not available and, of course, if you want to do a bit of shopping or have your nails done or something.
I am on maternity leave. My son will go to nursery 3 days a week when I go back to work and that will be in a normal nursery that we'll have a contract with, but for now he goes to this creche roughly one day a week and I get a bit of time to do the million and one things that are hard/impossible with a baby in tow.
All the staff are fully trained childcare professionals, it's been the same people there for at least the last 6 months and they give me a full rundown of his day when I collect him, just like any other nursery would. It's OFSTED registered and inspected.
I don't think there are many run on this model in the country and they are always at high or full capacity so I reckon the business is doing well.
As for your idea OP I'd say that as long as the market research shows enough kids in the area to fill enough to make a profit, go for it as childcare seems to be something that people are willing to pay well for. Have you looked at the Forest school model?