A Tent :P
Sleeping bags
air beds (don't forget the pump!)
clothes for all weathers
a good pair of walking shoes or boots with thick socks, you're gonna do a LOT of walking!
They're your basics, then stuff like:
torch
camping stove + fuel, pans, plates and cutlery, or you can eat from the huge array of outlets remarkably healthily, if not cheaply, if you shop around a bit
sun cream
ummm.... brain's gone numb, I'll let someone else add to the list...