People do meet in real life in Zealand, however most social activities for international people occur in Copenhagen and not in Roskilde. Locals also join in different social or professional groups according to shared interests. Often the events are organized through social media, such as meetup, facebook groups or through your work place. Danes celebrate almost everything and quite often alcohol follows along - and there is a chance your meetings ends with a beer.
You will find a few social networks for expats in Roskilde organized throughout facebook. The other provincial cities would do not have many meetings. Most people in Roskilde and Køge will also join Copenhagen social networks because of short travel time and more different events to visit and a huge variety of social meetings.
Sources:
ExpatArrivals.com (Danish section)
Worktrotter.dk
Internations.org
Meetup.com