We went expecting to explore the formal gardens as it was a grey day but instead undertook one of the park walks. It was about 4 miles in length and had some steep ups and downs along the way, but the views were fabulous and the bluebells gorgeous. A good walk for anyone with a little stamina and lots of things to look out for which would entertain little ones.
If you do undertake the walk, best to have a flask or a drink of some kind with you, as there are no cafe stops on the way around but a few at Polesden itself along with loos and the ubiquitous shop.