Having been to Europe, and seen the Light Pollution Map for that whole area, it is unclear to me how anyone could find true darkness there - anywhere. I suppose you take what you can get. I am familiar with high latitude darkness of the kind found in my native Canada, which certainly does have good darkness away from the cities, but suffers from cold which inhibits interest a good part of the year, same for Iceland I would surmise, and the higher latitudes of Europe.
In my experience, and travels, nothing compares to Australia. Let's be honest, the Southern Hemisphere night sky is significantly more interesting than the Northern Hemisphere. The narrowband imaging targets alone are a good reason to move down under, if that informs your decision making.
