The monkey forest is a drive from the main shopping/leisure bit. I actually really enjoyed it as the staff are very knowledgable and will explain interesting bits of monkey behaviour to you (obviously I already know most of this )
Kids play area is inside the Italian gardens which you also have to pay for but it is worth it. Play area is fab with arial runway, drive-on tractors, 'assault course', sand-pits and the usual climbing frame/slide stuff.
The ornamental gardens are also great for running around.
There are some display gardens including some little 'hobbit houses' designed by kids.
The barefoot walk is fun if you can brave it and the woodland walk with info about trees etc is also fun. they are also building a maze plus some climbing stuff for older kids/teenagers.
There is a cafe in the Italian garden also which is right next to the play area but maybe better to take a picnic. There are plenty of places to eat in the shopping area but all quite expensive and not brilliant.
In the main (free) bit, you can walk round the lake for miles (the start of the path is next to the public loos), take a boat trip, play pooh sticks on the bridge.
Oh yes, and there are countless expensive and daft shops, including a massive garden/leisure shop - this has a very child-friendly eating area with toys etc..
We find it good value for money and you can easily spend a day there.