Packo,
Flying in Europe is a piece of p!$$. If you head into France, clear in via Calais or Le Touquet. My recommendations down the west coast, La Baule (LFRE), La Rochelle (LFBH) and Arcachon (LFCH). South-east Bezier (LFMU) up the Rhone valley to Dijon - chose your airfield.
As Steve says, don't let the airspace chart of Belgium put you off, ATC are fantastic, access to Class B is rarely a problem.
PM if you want any more info.