My experience is that the theoretical courses are very thorough and exceed the JAA requirements. Study with AFT and you will have a competent level of knowledge that will be more than is required just to get you through the exams.
One of their Ground Instructors told me that they want to make the candidates understand well enough to be good CPL/ATPL's in the real world, and they are not just an exam passing pipeline. No disrespect to any other organisations was implied, just a quiet confidence in what AFT do.
(oh but there are always busy and your assessments don't always come back promptly!)