In reply to Enty:
We were queueing from about 6am-ish for camp4.
To be honest the other campsites are much more pleasant (leafy, green, etc), vastly larger pitches, generally flat (quite a large part of Camp 4 has a gradient), and in the case of Upper Pines rather near to the quality all-you-can-eat-for-a-tenner buffet in Curry village and best of all you can book in advance.
In terms of getting around there's shuttle buses all over the shop.