Departing for Trans Atlantic you need to call the tower for your oceanic clearance well before start time. Rwy 25 is pretty much unrestricted performance and you will generally get a turn on track to your first waypoint westwards, no SID to bother about.
You are required to get you oceanic clearance yourself. If you are unable call 118.3 about 40 minutes before with estimated time of blocks oceanic entry point requested and maximum flight level and mach number. Also your time enroute to ocean entry point and requested track(if appropriate). Of course this depends on you flying a jet...not something with props
