General information about how to arrive and depart from Antwerp is available from tourist info: www.visitantwerpen.be this site has travel info pages.
Antwerp can be reached from Brussels (Zaventem) airport by a special airline bus. It is a 50 minute drive.
There are also trains departing from the center of Brussels and they'll get you to Antwerp in 30 minutes. A high speed train is available from Paris and Amsterdam, the trip is about 2 hours.
You can get to antwerp from Brussels, Amsterdam or Rotterdam by River boat. For example, www.easycruise.com. Easycruisetwo cabins start from GBP9 per cabin per night. Alternatives include www.tui.com and www.saga.com for passengers over 50 years old. See Inside Page: Cruising the River
Airport: www.antwerpairport.be VLM www.flyvlm.com do flights into Antwerp. Airport is 2km from the city centre
There is a frequent bus service from the airport to the city centre from the airport.