I would think most metric sized Allen headed bolts would not be too hard to find in most parts of Europe (Denmark?)..... Unlike here in the US where there are still areas in our country (mostly in the "hinterlands") still seem to be stuck with SAE standards for tools and threading...
BTW, don't worry too much if the Allen head bolt you find does not have the non-threaded shank on it as it should work just as well. What is important is the length and threading and having a washer on it, if the original had one.....