I gather (from an American woman taking her dog across on the midnight crossing before the Marseille game) that the Newhaven-Dieppe ferry is the only crossing that you're allowed to go across without either a car or a cabin booked.It's quite telling how those that want 'this' so quickly lose sight of what bought them to the table, in order to play their favourite yet completely unwinnable 'game', again.
Somewhat unedifying for all concerned.
Thus presumably it's the easiest to go on with a bike (hence me replying to you specifically).
But to give some context for this story, it costs £31 to get the ferry from Dieppe to Newhaven as a foot passenger.