Hello Tilia!
Look for the works of Robert Hart and the book by Patrick Whitefield, I believe it has the name of "Forest Garden".. Both are in England, so should have a lot to say for your climate...
Also look at the database of the English Organization "Plants for the Future", which should be immensely helpful. I suggest you volunteer for them to get first-hand knowledge.
I imagine that your system will be apple-based. What I know of this system: Apples need to be in the full light, under them you can plant plums, and at ground level the small berries, you will probably find many different ones. A friend in Switzerland was eating fruit from May to OCtober from his mixed berry patch.
In Switzerland there used to be many different apples, which were the base of the diet before potatoes were introduced. There were apples so sweet their syrup substituted for sugar, apples for baking, for roasting, for feeding to the animals. There was even one little apple, not very tasty, but could be stored for two years in case of a failed crop. It could be a basic element in your diet.
Many of your "weeds" are edible, from dandelions to plantains, Queen Ann“s lace, amaranths, purslane, etc. Many of the wild cousins of our garden crops will be found around your garden: mustards, wild lettuces, remote ancestors of beets and cabbages.
Spring nettles are delicious if harvested very early and sauteed. We ate tons of these when I lived in Switzerland - probably one of the most nutritions plants possible. When young the sting is transformed into protein after cooking. Also nettle beer, made with brown sugar , ginger, and nettle tea, fermented a week or so with bread yeast. Hmmmm...
Go after the root crops- most can be stored all winter.
Go for it!
The Permacultue Associations are quite active in England- I think you will find heaps of people and information there that will be pertinent to Denmark.
Good luck!@
Marsha in Brazil
www.marsha.com.br