Hi Nobby, did wonder why you were not with us for this race as you appeared to be rather keen to take part
The on-line key is stored in the registry. Run regedit and look for HKEY local machine - software - 10tacle studios - GTL - keys and this should contain your on-line key.
I think it is also stored on Steam (if that's where your GTL came from). I think you have to find the game in your library and right click on it and look for "view online key" or some such wording.
Enter the key using CAPS for the letter, with NO hyphens (dashes) between them.