In reply to robal:
Went Dover-Dunkirk on DFDS on 18th July - delayed due to avoiding M20, as we went M2. When that snarled up, we went cross-country for the last bit. Missed our crossing and had to get the one 2 hours later, which was delayed a further 1/2 hour, which wasn't ideal, but not the end of the world.
No problems coming back on 26th, although Dunkirk ferry terminal is a miserable place to spend any time.
My wife, her parents and our little one are booked on the Channel Tunnel in September. Think F-i-L is seriously considering changing the crossing to Portsmouth-Le Havre - can't imagine why he didn't do this in the first place, as they're staying around Deauville! As it is, they'll be driving miles more than they need to.
Post edited at 22:39