In the summer of 2013 we had the opportunity to visit the Longleat Safari Park in Wiltshire http://www.longleat.co.uk/ and had a ball.
Whilst it can be pretty expensive for a large family there are lots and lots of things to do, see and have a go at.
We haven't been there for a few years and we found several new areas to visit but the old favourites are still there like the Boat Trip around the lake, the Jungle Railway and of course no visit would be complete without a drive around the Safari Park.