Thank you so much for your quick response and excellent advice which has worked as you suggested. After deleting the theme-my-login.php file I am now able to enter the wp-admin area.
The TML plugin has now automatically been deactivated, so I guess I have to delete ALL the TML folders/files and completely re-install again?
The only changes I think I made was to click a Check Box that restrited access to wp-admin in the Themed Profiles section? But the Admin User was left unchecked and so i would not think this affected any Admin User? I guess it should be impossible to block Admin User from the admin section?
I am most grateful for your help in unblocking the access. Thanks.