piginsh1t,
I can speak for AF but not for all the French.
No Captain would allow visits to the cockpit as it is the rule. We have a locked cockpit policy that until now I didn't see anyone breach. However most Captains accept company staff on jumpseat (priority to pilots and CC).
If someone wished to have a look at the cockpit before disembarking, I would suggest asking a CC before descent because it requires some asking. The cockpit crew are always very busy with ramp agents, technicians, fuel etc while pax disembark, and I expect that a request at that stage wouldn't be welcome.