Chris
If you can get hold of Rex or Barbara vis the website/email and tell them that you want to do all the arena events, then they might be able to get space reserved for you, if you camp in the America's field then it is normally first come first served, if you can get in the Marshall Field? above the re-enactors then that would be easier for getting to the arena, for that try contacting Malcolm Dunlop on events@imps.org.uk he is the "Field Marshall" for that one and may help out there, probably your best bet if you explain nicely