Roxy, CPL flight planning/operations, from what I can remember, actually had some useful stuff.
ATPL flight planning is all about preparing a fuel plan that no-one actually uses in real life (even the remaining B727 operators) and certainly don't prepare in the way the subject is examined.
It is a purely theoretical exercise that can be happily forgotten immediately once the exam is passed. It has absolutely no practical application.
Roxy, just seen your further question. I have had friends who have self-studied it successfully. However, they had supportive partners who allowed them to have time during the evening to study. When I tried to self-study I hit a brick wall and in the end I had to go to AFT and do the course there.
You do learn a lot of exam tricks by going there which you don't get in the notes. It is also a great place to network. The rest of the subjects can be self-studied satisfactorily with possible exception of Systems.