You can travel to Ven by ferry from Copenhagen, or you can use the ferry from Landskrona, operated by Ventrafiken.
You can bring a car on the ferry from Landskrona, but it costs €70 one way, not including driver or passengers.
Time table for the Landskrona-Ven (Ventrafiken) ferry:

a) Not Saturdays, Sundays and Public Holidays b) Not Christmas Eve
c) Not New Year’s Eve d) Not New Year’s Day