Flying_Steph,
I wouldn't go on a LGW-MCO with Virgin all ready with lots of B747-400 questions, because our man will be on a Classic! Us Classic drivers aren't that happy to be asked why we haven't got lots of TV screens, and why we occasionally have to fly the aeroplane manually!
Seriously, there's some good advice above. If you can collar the IFS (female - black blouse; male - grey shirt) you will get the most direct CC route to the captain. Be nice, explain your interest, and you might be lucky!