I did it over 5 days with my brother in 2016 but that didn't allow much stopping time but if you don't have time on your side and don't mind between 130-180km a day, that's an option too. You pretty much don't cycle on a road for the entire European leg.
We caught the overnight ferry to Harwich then rode to Chelmsford to break the journey up for the children. Back to London today.