Try to list yourself ahead of time while you're still in the states by calling their resv number. When you show up at LGW, go to the "Ticket counter", not the check-in counter, and tell them you're gonna "staff travel", and they should know how to issue you a gate pass, and collect your hefty departure tax. Once you get thru custom, then it's just like JS anywhere: introduce yourself, try to get world business class, and drink champagne till you land.

Have fun!