We went a few years ago and it is a good day out.
Please DO NOT take your car into the monkey bit though! We did, to amuse little dd. Yep, she was amused all right at daddy's diatribe about the monkeys as they took huge monkey sized bites out of the back spoiler trim on the car.
We were given this tape to play in the car which explains what you are viewing as you drive round the safari park. DD used to like listening to it regularly when we got home; quite a bizarre thing to listen to when you're not actually there anymore!