Went there today.
www.manorhousewildlifepark.co.uk
Ok to be fair Folly Farm in Pembrokeshire represents better value for money, but if you've done Folly Farm it's worth looking at Manor House. It's £8 for adults-children under 3yrs old free. Other children £6.
It was very quiet when I went today. Has baby change facilities (although only one as far as I could see and in the disabled loo),and a nice playground. Also has a hay barn for older kids to jump around in.
They have some sort of mini-safari things where you can walk through the animal enclosures and get really close to wallabies and ring tailed lemurs. Although if you are squeemish you may not appreciate a lemur hopping on your buggy. Lots of other animals apart from the ones mentioned.
Had fun there