I couldn't get the expansion to work at first. I have the disk version of the vanilla game and was told that the expansion would work with it.
I tried copying the expansion over top of the vanilla folder. Running the exe just result in nothing happening.
I also tried reinstalling vanilla in its own folder and downloading the expansion into a different folder. But, launching resulted in an error - "This application has failed to start because DebugMsg.dll was not found. Re-installing the application may fix this problem." This lead me to think that it needs to be applied over top of the base install.
Then I got to looking into the root folder. There's a file in there called ########.log. It looks like it's a launch debug file. At the end it shows a launch failure... "Exception:Error openning package file [READ]

ata\1captain.pkg". That's the file for the low res UI (800x600). So, I reinstalled with the low res UI option checked.
That fixed it! Hope this helps anyone with the same problem.
Also, sorry that the Europeans can't buy this, but I'd wait and see what happens. I'm sure that Stardock has no control over this else they would be offering it. If we have it here in the states, surely it's coming to Europe, too.