In 2 to 3 hours from Brussels you can reach some varied coast line in France. One of the advantages is to avoid the traffic that often plagues any drive back and forth to the Belgian Coast. The other is to see for yourself some of the images you have etched in your mind: the changing houses, the Art Nouveau houses, the chalk cliffs and towers of seafood.
From October ports such as Le Treport start landing scallops. Delicious sautéed with garlic in 3-4 minutes in a hot pan.
For bird lovers the Baie de la Somme is the site of a well known parc, the parc du Marquenterre. So with its mix of cliffs, pebble beaches, sand beaches and mud flats this area offers a good mix of scenery for the hikes to come before of after the seafood feasts!