@David-Buttery Thank you for sharing your route. When I use the plan.tomtom route planner I also see the same issue, so obviously an error in the TomTom map.
17d8b006-59cd-43ff-ad0d-a300afa82c92-image.png
I have reported the error to TomTom, you can do the same here: https://www.tomtom.com/mapshare/tools/new/mapshare/#loc=53.96705,-2.44067,19.5