In case people are worried that they won't be able to camp if they don't have tickets - it's always possible!
I have been 5 times and have never booked. The last 2 years we were in Camping Bleu (actually I think it was the huge Parking Bleu right next to the official Camping Bleu, that gets used as an extra campsite) and there was no requirement to have tickets - we just bought them on the gate.
We got there on Thursday and it was mostly empty, it only started to fill up late on Friday.
Pete