Hi riemb,
I can recommend Flightworx. They have provided trip support several times for me on flights over Europe, N.Atlantic, N.America, Russia, China, India and the M.East.
As well as the usual ATS FLTPLN, MET and AIS, they arrange overflight permits, landing permits and also have an excellent fuel shopping service.
They will tailor their products to fit your requirements. Find out more at:
FlightWorx | Trip Support Solutions