Muddy routes are often given by Google maps too. I’ve spent quite some time on dirt tracks in northern New England when following a Google bike route.
Might do LEJOG next summer as my family want me to visit the UK and it would be nice to combine that with a bike trip. I rode in the UK when I was young and also rode from London to North Yorkshire a few years ago. The roads are fine, just do what you’d usually do an avoid main roads with fast traffic. I stayed in motels, but for LEJOG I’ll probably combine hotels, hostels and camping.
Yes and Google Maps will divert you many kilometers/miles out of your way in order to put you onto some bicycle path or MUP that takes you even further out of your way. LOL
Cheers