York (UK) - Münster (GER) in four days, including ferry.
https://www.yorkeuropean.uk/munstercycle.html
https://www.muensterschezeitung.de/l...enster-2595151
Edit. I wondered how they managed to do the trip in four days when the navigation software gave me a distance via Dover ferry of around 1100 km. I mean - due to the long time to sit - it would be painful. But the German newspaper said they boarded the ferry already in Hull and unboarded in Rotterdam, so them clever Brits snipped a very huge chunk out of the trip distance. York to Hull and then Rotterdam to Münster in 3-4 days - that is doable. I got to Enschede, Netherlands, on bicycle myself, back and forth in one day, around 150-160 km.
Edit 2: York and Münster are "partner cities".