A long drive, so an early start
From Bruges and the coast, the road to Brussels Airport (Zaventem) follows the E40 almost all the way: past Bruges and Ghent to the Brussels Ring. From the Westhoek, around Veurne, De Panne and Nieuwpoort, you first join that route via the A18. It is one of the longer drives to Zaventem, and in the morning rush traffic can build up badly around Ghent and Brussels. Choose a pickup time with a generous margin; for a morning flight that often means setting off in the dead of night.
The good news: you can simply go back to sleep on the back seat. For low-cost flights from Charleroi the drive is a little longer still, passing Brussels and heading south. Schiphol, Eindhoven, Liège, Düsseldorf and Cologne Bonn are available too. The price table on this page shows the fixed fare from your town to every airport.