Newhailes House is in Musselburgh, which is on the outskirts of Edinburgh. Built in the 1700s as a family home, it's a lovely home with gardens and woods to stroll around. The NTS has made a huge effort to provide facilities for children with a few crazy golf holes in the courtyard and an enclosed play area (£4 per child at the time of our visit).
The courtyard entrance is home to the shop, cafe, and i believe a potter at the weekends. There are a couple of options for the guided tour, so I'd recommend booking a timeslot in advance.
The house is not as large as you might expect from the outside as it's only one room deep, but there is still plenty to see. The main floor has beautiful period furniture and collections as you would expect, upstairs is a little more modern as this is where the last Lady of the House lived until she gifted it to the NTS. Surprisingly, it didn't come into Trust ownership till the late 1990s and opened in the early 2000s.
There are stairs up to the main entrance and again inside to the upper floor so not wheelchair accessible. The courtyard, shops and cafe would all be accessible but not the house itself.
There is a couple of walks through the woods and grounds which are popular and not too long with some beautiful scenery. We got the impression some people come to visit the grounds which would be free of charge, without visiting the house.
All in all a lovely house and worth the visit.