A quick search of some Danish sites brought up Både til salg - hbs
and Fini Lund Start
. Both seemsto be based close to Copenhagen which is in the opposite end of Denmark
of Frederikshavn. Fortunately Denmark isn't that big, so it's only a 5-6 hour drive each way. You might be able to use one of them, or have them recommend a colleague located closer to Frederikshavn. I don't know anything specific about these surveyors other than the fact that somebody referred to their address and that their website gives a good impression. This means that you will have make up your own mind and not rely on my reference as a recommendation. In spite of my lack of knowledge of this market, I thought you might be better off with these links than without.