Firstly, thanks for getting back to me. I do have a little follow up.
I have tried removing the docker, removing the folder and then installing, with the same problem. I have also removed the config file, and restarted, only to have the same problem. Going through the forums here I'm not the only person to encounter this problem, only none list a fix. An example is lexcomman above me who even refers to others he has seen.
Is the config file copied elsewhere and being retained through fresh installs?
When opening the WebUI via the docker control interface, I get a "This page isn't working" (HTTP ERROR 401). If I click into the address bar and hit return the login page will open. I have already set chrome to allow popups and redirects for the address and port to get this far. (Update, the same problem is being experienced in Firefox, the address must be manually confirmed in the address bar there too.)
This may be fixed when I can finally login then.