I'm currently changing from the use of Cart66 to this plugin for a client of mine. My client is based in Northern Ireland (which is a part of the United Kingdom) and I was disappointed when I noticed that not one of our 6 counties have been included in the Base State/Province/Region.
I would like to help you in stating that the 6 counties are the following and I would expect these to be included in the next update:
County Londonderry
County Antrim
County Armagh
County Down
County Tyrone
County Fermanagh
Cheers
Tyler