Hello Axel
Tha DFDS has published some book about the companys ships and history.
You can find and order the books on the website
http://dfds.com/DFDSGROUP/EN/Top_Navigation/Order/books/The first mentioned book" DFDS 1991 - 2006 - Ship development continues"
contains information about the most of the passenger ships in the company.
There are a lot of general plans of the most of the ships.
Winston Churchil is mentioned, there are only few plans of the ship, but there are a lot of nice photos.DFDS have had 3 ships with the name Dana Sirena .There are general plans of some of them.
Best regards Bjarne