The Thistle and Shamrock is a great program, in my opinion, but you must realize

it is not focused on unaccompanied singing.

You may hear that once in awhile, but not the majority of the program. In case you didn't follow the links at that NPR page, here is how to listen to the program internationally:

The Thistle & Shamrock® is distributed throughout Europe via America One, Fridays @ 1700 Paris time on the Astra satellite, and worldwide on the American Armed Forces Network, Saturdays @ noon Berlin time/1900 Tokyo time.

For a satellite/cable listening guide contact NPR Worldwide,
635 Massachusetts Ave. NW,
Washington, DC 20001, USA
(e-mail: worldwide@npr.org).