Looks like a last minute change to travel plans is needed! The weather forecast at the moment is full of weather warnings about heavy & persistent rain and the maps look like it is going to be right across the route I had planned (Chester, Stoke, Leicester, Huntingdon, Stortford).
Attempts to contact the Steam-packet took ages and when I did finally get through, the message said their office was closed!
So instead of altering my booking, I made another one for Thursday morning.
Of course, this now means I have practically no food in the house as I had timed it all ready for leaving tomorrow! Break out the soup!