You need CAA to confirm that the TRTO is approved by them, and that it is ok for you to go ahead with the training there! Also try to get confirmation in writing, take notes, who you speak with, date and time, so you have some reference and records.
Base training company also have to be approved, make sure you find out by the CAA ALL records and documents they do require!
A good TRTO will know this, but it is your responsibility to verify it to make sure all is done correctly.