To get into the castle, you need to pay, but I think you could enjoy the grounds and gardens for free. There is a car park charge. You could also take a minibus from other local NT properties or do what we did and take a boat from Ambleside and make the 5 minute walk from the jetty to the castle.
Once we were in the castle every room had something fun for kids to do, including building castles from large foam blocks, craft activities, a microscope room and dressing up costumes (for adults as well as children!) There was a full sized pool table in 1 bedroom and a table tennis table in another. One room even gave us chance to write the name of our favourite books on the wall. None of the furniture was original or precious, and there are no valuable ornaments.
There is a pop up cafe in the castle, serving drinks, snacks and sandwiches which are prepared by a local pub. We took our lunch to one of the picnic benches at the front of the castle and enjoyed a sandwich with a view.
We spent about 4 hours there and could have spent longer. We didn't try the croquet on the front lawn or the children's trail, and it wasn't quite warm enough to paddle. But I'm sure we will be back.
Round up
Cafe latte price: not available, but £2.25 for a cappuccino
Favourite cake: scone, cream and jam (this is the National Trust after all) £2.95. Tray bakes also looked very good.
Child friendly highlights: Every room has something different, adventure playground and access to the lake. And try the baby change in one of the towers - very posh!
Buggy friendly: a sturdy buggy would be fine.
Parking: there is a charge, but we came by boat.
Verdict
We had a great day out, and liked the very relaxed approach. Every stately home should have a table tennis table!