Hi there, good to see at least there is one more Healey nut going across, there has been a serious lack of healey's in the past, can't help with tickets I am afraid, but as this is my 21st year and I havn't got mine yet, I wouldn't worry too much. camping permits can be had here or even at some of the travel companies up to quite close timing. Sleeping in the car is fine, but I wouldn't want to sleep in my 3000 that's for sure.
Worst case would be to take a bed roll and get some kip by the side of the car on sat night, I wouldn't bank on getting much sleep though.
have a great time, believe me you will be hooked.
Steve