I can reccommend Lincoln Farm Park in stanlake, oxfordshire. I have been there twice now. Last time was a few months ago with a 4 year old and 2.5 year old.. They have a nice playground with a climbing frame for little ones and another for bigger children..(both of mine went on big one) They also have 2 indoor swimming pools for an extra cost(though not tried them yet) They also have a playing field... There is a little area where there are a few rabbits and chickens.. And the Toilets/ Showers are very clean and there is plenty of room for changing in the cubicles.