With over 100 species spread around 100 acres, you should aim to spend at least half a day exploring. Some of the first animals I encountered were the white rhinos, called Rumba and Rumbull. I was impressed at how close I could get, with Rumbull posing for the camera only a couple of metres from me.
It's worth walking around the main part of the zoo at least twice, as you'll see a lot more that way. The elephants were quite distant the first time round, but we eventually had a great view at feeding time: