There are no nonstop flights between London and Belgium's primary airport, Brussels (BRU). The ~350 km distance is too short for viable direct commercial service; high-speed rail (Eurostar, ~2 hrs) dominates.
Flights require a connection, usually at:
Total journey time: ~2–4 hours (including layover). Actual flight segments are 45–60 min each. Most travelers choose Eurostar for city-center-to-city-center speed and convenience.
Charleroi (CRL) and Liège (LGG) serve low-cost carriers but also lack direct London links. For essential air travel (connecting onward), book a through-ticket to protect against missed connections.