Hey sirius! It seems that at the moment Tamnavulin is, as expected a UK only brand. However, the good news is that the Tamnavulin Distillery has been re-opened (2007) and is producing at full speed! It will though take time before there's enough stock (needs maturing!) to go in to other markets.
Have you looked here:
http://shopwhisky.lovescotch.com/res...age=0&x=25&y=9
While the 12yo is not available, perhaps some of the others may pique your interest!