Fuji,
Thanks, most of us are always happy to try and oblige.
If we say "standby" on first contact it's probably because we're on the telephone, you'd be surprised about how much time is spent on landlines, or because there are one or two things to be said to the IFR stuff first.
I would just suggest your first call is something along the lines of "Gatwick this is G-ABCD requesting zone transit".
That way the person at the other end of the radio knows exactly what you're after right away and can prioritise accordingly.
WF.