Are you going on one of their special photography days or just turning up? The special days are expensive (£75) but are well worth it as you get to go into some of the enclosures - wonderful for the foxes and wildcats in particular. They also take some yummy snacks to get them out in the open. You can see some of my images from my trip
here.
I'd just got my 300 f2.8 so I used that for everything, but I wish I'd had something a bit shorter for when the animals got very close. Indeed, it was that day that made me decide I needed a 70-200 of some type. So your 300 f4 and 70-200 are the ones I'd recommend. I'd probably bring the macro as well.
If you're not going on a photography special then you'll still be able to get good shots of most of the animals. It's really only the wildcats that would prove to be a problem. Oh, and the otters do seem to kip a lot when they're not being fed.
I hope you have a great day.