What I've actually done now is look at the options from Liverpool airport, and there are direct flights to Amsterdam so, hopefully, avoiding the queues at Manchester, which was the purpose of trying to find a rail/sail ticket. So I will end up on a train..but from Amsterdam to Haarlem! That will be in early July; and if things are still bad then r/e airports then I'll seriously consider Avanti to London, overnight, then either the Newhaven ferry (sounds good) and a couple of days in Dieppe, or Flixbus and a couple of nights in Brugge for my August break. So thanks for the heads-up!!
I never go to (say) the Med in late July or August due to the crowds and hiked-up fares/hotel costs.
With the state of the airports Eurostar and the coach companies should be making real capital out of it, at least getting pax to the near continent.