Toph said..
To charter in the Med, or anywhere else in the world these days you will need the RYA ICC certification. It is essentially the old Comp Crew but I believe just slightly more involved. As usual it is an insurance requirement and a bit over the top in my opinion. Even if you have a higher certification, believe it or not you still need the ICC (although it's just a paperwork and money issue).
Bareboat charter has always required some form of formal training.,
This is not actually the case. I sailed in Croatia this summer using my RYA Ground Based theory certificate. Go figure.For croatia there is an official list of recognised certificates. They strangely list the ground based course as one of them.
Other med countries ask that the skipper is 'qualified' but do not produce any official list.
The RYA and ICC are different governing bodies.
However, for the sake of my silly argument, I would completely agree the ICC is the way to go. You would be mad to hire a yacht with no previous experience using a theory course as your qualification.
If I were the original OP, I would try and get some basic sailing skills under my belt, then go straight to the ICC. The RYA Competent Crew has its place but doesnt really get you your ticket to the med yacht. Its a bit of a non-qualification unless you want to go further to the RYA Day Skipper.
ED