Found this website the other day and thought it may be useful to some: https://www.motogoloco.com/map/
I usually use Tyre to create my route before loading the itn file onto my Tom Tom one. But because I was on the work computer, I couldn’t install Tyre so needed a web based planner to plan my route to Cheltenham. You’ll need to register (use fake e-mail if you want) to be able to save and export routes.
Have a feeling it may be possible to search for routes others have created but I haven’t really looked into that.