Plenty of groups on the forum to try and get on board with who organise their camping and other stuff to do, but there are also plenty who travel solo or with a few mates, having booked camping beforehand either through the ACO direct or one of the agencies and then hook up with others at the favourite haunts out there. Falling into the latter category, I have no particular suggestions on groups, but wander the forum and the CA guide and see what you think suits best,
Mark
