VFR Departure Class Bravo Airspace

As far as I know, anytime you are going to set your feet inside of a Class Bravo airspace you need an ATC Clearence. No matter if you are arrivng, departing or just passing through the airspace, you need that. In Flight Simulator you can ask the ATC a Clearence for transitioning the airspace when you intend to enter it when flying from outside. My question is, what about when you want to depart from within the airspace? How do you get your VFR clearence? when departing VFR, your first atc menu option is requesting taxi for a given departure direction but no Clearence request option is available. The first is "request taxi-(direction) departure" Can this "call" for taxi with the departure direction be intended as a requesting of Clearence? Another information that I got from FS documentation, was that when you are taking off within Class Bravo airspace the ATC behaves such as you are recieving Flight Following service automatically. Can this be interpreted as an "automatic clearence"? Thanks for the help.