Next June I am going on my first ever european ride with some friends to France

(who have done it several times before).
Nothing to fancy, just a long weekend, probably thursday to tuesday. I've always flown before so riding there on the bikes will be a new experience for me! We're catching a ferry from Dover rather than the Chunnel and will be using campsites at night, popping into town for food once the tent's up. What I'd like to know, apart from riding on the right and talking funny, what else should I prepare for and what gems of wisdom can any wise old travellers impart to make my trip as smooth as possible? What is essential equipment and whats not etc. Any advice gratefully recieved.
Over to you.