Hi, I have a lot of experience of Belgium because my wife was Flemish. I learned the language, and eventually worked 15 years in The Netherlands. A word of warning, the different language groups in Belgium don't get on together; and, if you come out with the wrong language in any part, they'll asume you're from the other side and be hostile. No problem if you take note of the language being used on the road signs. In Brussels, stick to English: it's the safest (even for the King), and most people there understand English because it's the European capital. English is EVERYBODY'S second language in Holland.
Wiffle the Wuff