I've been involved with ro-ro shipping for over 40 years in various capacities, and have sailed on many vessels in Northern Europe. The quality of accommodation for truck drivers varies considerably from company to company. If you travel on DFDS vessels, for example, you are pretty sure of good accommodation and food, even on chartered in vessels, as reputations are at stake.
Accommodation is usually in two berth cabins en-suite, with a few ships having a mix of two berth and singles. Food is usually what the crew gets, often solid but plentiful. Recreational facilities are usually limited, but, as most routes are either overnight, or under eight hours if daylight, and most truckers use the time to sleep, as they will be on the move as soon as the vessel docks, so it is important to them to make the most of the crossing. Most ships are now dry, but truckers accept that. They usually have some private mess area with a television and video's, and maybe even internet.
There are currently no routes in NW Europe that carry accompanied trailers over 30 hours, and then that is only the weekly DFDS sailing between Gothenburg and Immingham that goes via Brevik, the direct route is 24 hours.