Simon, not sure if you’ve read the OP correctly. He’s IN Boulogne going TO Holland !!! on Sunday, (today)
I think that you should have a look at your reply again
There is The Corridor, the A16 from Belgium down to the ferry ports.
Surely you mean UP to the ferry ports
The ban in France tomorrow starts at midnight tonight through till 10pm, according to traffic ban.
Todays ban finishes at 7pm. If you can, get up through France tonight, now.
WTF was that all about