Thanks guys.
Yeah, I should have mentioned, I meant for VFR flight.
So generally speaking, contact ATC once airborne for clearance?
But I can contact them whilst taxiing but they may not give me clearance until airborne?
Some of these CTAFs under the steps at Melbourne are quite tight, eg terrain 500 feet below and class C airspace 500 feet above.
Cheers,
Sheldon