Just ask the crew and tell 'em what you've posted...
You might be lucky, and you've got nothing to lose. Although no one admits, it's definitely easier to get on a jump seat in Europe than in the States...
NB. But just don't show up in uniform and FAA license! That's ridiculous! Most Europeans do think different than Americans in this matter, and pilots do not usually walk like wannabe-heros in uniforms around as in the States... (just my thoughts...)