Sherrill Farmhouse is in Dunterton, right on the Devon and Cornwall border. It's a big old farmhouse, part of a group of cottages converted from the original barns. You get the whole house to yourselves, and it's on about 16 acres of land.
It sleeps 22 people. There are seven bedrooms and five bathrooms. It's got a 4 Star rating. It's comfortable and well-equipped, but it's a farmhouse, so expect it to feel like one.
The main thing here is the shared leisure facilities. There's a large indoor heated swimming pool, a hot tub, a gym, a bowling alley, and a games room. They're open until 9pm. Outside, there's an all-weather tennis court you can hire rackets for, a kids' play area, and a few ponds. One is for wildlife, the others are stocked for fishing.
The location is good for exploring both counties. You're about six miles from Tavistock, which has a proper market. Dartmoor is on your doorstep for walking. The Tamar Valley is nearby too, with places like Morwellham Quay.
Useful links if you're planning trips: Dartmoor National Park and National Trust Tamar Valley.
For facilities, it's got what you'd need for a big group. Washing machine, dishwasher, woodburning stove, WiFi, TV. Bedding is included. There's on-site parking. You can bring up to two dogs.
The nearest pub is about a mile away. The closest shop is four and a half miles, so you'll likely want to drive for a big shop.