There's clearly no perfect way of doing this. I would suggest:
Scandinavia (incl. Iceland)
BeNeLux plus France north of Paris
Germany, Switzerland, Austria
Eastern Europe (i.e. Poland, CZ, Hungary, Baltics, etc.)
Southeastern Europe (Slovenia, Croatia, Bulgaria, Greece, etc.)
Southern Europe (France south of Paris, Portugal, Spain, Italy)
Middle East
Africa
Not perfect, obviously. You could add Italy north-of-Milan to the Germany, Switzerland, Austria section. Makes sense geographically, but not culturally. Or you could add Greece to the Southern Europe section. Makes sense historically, but not geographically.
Nothing works really cleanly, so I would split as few countries as possible into multiple chapters. France being the obvious exception.