The Tiling Courses Feedback forum has been online for over a year now and has some really decent comments on the good training centres.
http://www.tilersforums.co.uk/tiling-courses-feedback/
If a training centre isn't listed here there's a good chance it's not worth booking on or is too new to dare and trust your future with. In my opinion.
I'd only book with a tiling course with good feedback here:
http://www.tilersforums.co.uk/tiling-courses-feedback/ or one that's bigged up here:
Tiling Courses | Wall Tiling Courses | Floor Tiling Courses UK
Note: Please dont link to courses that are not sponsors of the forum.