I guess I was being preemptive and it has not resolved the issue I will continue to try the repair feature, but I believe my Zenimax Folder is missing and maybe the cause of this.
Bother - I forgot to say that I can't find a new 'Bethesda.net_launcher.patchmanifest' to download anywhere, I'm already running the game as adminstrator.
Ah ha! I can launch the game from the eso64.exe, but my launcher is still broken. Which is fine, except I'm concerned about the PTS, because I can't update the game at the moment.