Newton Manor House is in Swanage. It's on a normal residential street, not isolated. You can walk into town in about 20 minutes, or it's a short drive.
It sleeps 16 people. There are eight bedrooms and nine bathrooms, so no one should be queueing. It's rated 5 Star, which it needs to be for a house this size. It's a proper big house for a big group.
The house is very old, early 1600s. It's made from the local Purbeck stone. There's a lot of original wood panelling and carvings, which is nice. The main rooms look out over the garden. The upstairs bedrooms have views over the town to the sea.
The garden is walled and landscaped. It's peaceful. There's a patio and a BBQ.
You're about a mile from Swanage beach. It's sandy and good for families. The town has all the usual seaside things: shops, places to eat, a small theatre. The steam railway runs from Swanage to Corfe Castle, which is a nice trip.
For walking, you're right by the coast path. Durlston Country Park is close, with good cliff walks and the lighthouse. You can walk north to Studland Bay, which is National Trust. The whole area is good if you like being outside.
Inside, it's got what you'd need for a large group: plenty of bathrooms, a washing machine, dishwasher, WiFi. Bedding and towels are included. There's parking on site. It's set up for Christmas if you're thinking of that. No pets, I'm afraid.
Useful links for planning: National Trust Durlston and Swanage Railway.