This a little further from Ampthill, and certainly different type of day out. I admit I went as 'helper' with the school quite a few years ago, and wasn't sure if it was going to be my thing. But it was lovely wandering around seeing the enormous pieces of art that Henry Moore had produced.
So if you love statues then it is worth a visit. There is also an exhibition of screen printed fabrics that he also designed. You can defnitely lose yourself around the grounds on a lovely fine day, I wouldn't recommend going in the rain. They have a website and the facilities have changed since I went it is looking great on the website www.henry-moore.org, it opens for the season on 1 May.
There is a place to eat a picnic, or I would recommend combining the visit to Hopleys plants it is a lovely nursery with extensive grounds and a really nice tea room, selling homebaked quiches amongst other things. It is only about 1 mile from Perry Green.