FF, at the risk of taking your thread off at a tangent (wouldn't be the first time.......), are you actually planning to fly this route? If so, in what?
I ask because I am thinking of a trip to Stockholm which is only up the road from your destination, but have ruled out going across the north sea as beyond my abilities.
My best guess at your latest question is no. Yes you will of course file a flight plan since you are going over several FIR's and that might smooth your path (they know you are coming), but transit negotiated in advance?? Don't think so.
In any event, let me have an answer to my questions if you will.
The Wombat