From a french RCA (law) point of view, this is not the type of clearance you should get.
It should be something like: "Callsign, turn left heading XXX to intercept LLZYY, report established"
Once established: 'Callsign, descent altitude zzzz ft, clear ILS approach Rwy YY"
The 2 can be in one message: "Callsign, turn left heading XXX to intercept LLZYY, when established, descent altitude zzzz ft, clear ILS approach Rwy YY"
Obviously the "descent" part wan be removed if you're already at the published altitude ti intercept the GP
Anyway, if you get the message you were talking about, just keep in mind that (at least) in France, when you're under radar vectors, the ground clearance is provided by the ATC.
As this vectoring ends once you're established on the LLZ (or VOR radial...)of the procedure, you should NOT start your descent before being established on the LLZ. Then, you're on your own, you can descent to the published altitude, or follow the glide when you find it
I don't know if it's of any help to you, but just remember: You can still ask the ATC if you're clear to descent
