Biggest European LEGO event?
The main show that Lego release new sets at every year is the Spielwarenmesse fair in Nürnberg (Nuremberg, Germany). If you watch the various forums, especially www.EuroBricks.com, you'll see excited posts like this one about Star Wars around the time of the fair. Lego also announce sets at the New York equivalent show.

Models made by fans are usually displayed at Lego fan events rather than big trade fairs. The trade fairs are about marketing and showing things off to retailers. There's a bunch of jargon you might find handy, the main terms being AFOL = adult fan of Lego, and MOC = my own creation. Both defined on this site:

What does &quot;AFOL&quot; mean?

What does the acronym MOC stand for?