When I am on the main page, and click on "KØB" button, I really expect to get one bottle of water for the price that was on the main page. I go to shopping cart and see that I have to by minimum 20 bottles.... Is it good? NO. :-)
Make it clear for visitors what exactly you are selling. I am also not interested to read lots of text on main page. I want to see products. Make pictures bigger, out with all text that no body read.
Meny in the header. Make it visible. Make "Kurv" visible. Light grey color on dark grey...