Rupert,
Ferry at 7??? Go for the Tunnel shuttle, only half hour earlier at 6:28 (plus 30 mins check in time, so 05:58) and it will be full of Alpines.
How much for the ferry? Shuttle is only £39 for a day return when booked on-line 24 hrs in advance and the return time is fully flexable.
For directions, go to
www.viamichelin.com , get the route from Coquelles (calais) to Croix en ternois. Click on the little plus sign to get a blow up of the
62 miles, 1hr 11 mins, the route looks simple enough with a 4 Euro toll (payable at the J5 exit of A26).
Or if your on the A3 around 5am, I'll pick you up in convoy ???
Simon.
PS: PM me your email account and I'll reply to you with a .prn file of the route.