Good point BillyM -ie. you should really take your logbook with you. I guess another factor may be the airline you fly with.
Last April, before I started my PPL training. I was flying back from Washington to LHR. During the cruise, I mentioned to the steward that I was interested in starting my PPL and could I visit the F/deck?-off he trots upto the cockpit. Within 10 mins. I get summoned up.
The crew where fantastic and very enthusiastic about humble me starting my PPL. -I spent about 20mins. or so up top and then excused myself. The a/craft:B747-200 and the airline in question ...BA -Thanks Guys!