Hey Simon,
To add any country that is not currently listed, you would have to head to this file within your Events Calendar plugin files:
the-events-calendar/common/src/Tribe/View_Helpers.php
In the function there called constructCountries(), you can see the list of current countries and add/remove any items you would like.
I hope this information helps!
One thing to note, as well, is that this forum is our “Pre-Sales Questions” forum—for any further technical questions/bug questions/etc. please post in our free forums here → wordpress.org/plugins/the-events-calendar.
(Or, if you have a premium license here, please log into that account on this site and post in a premium forum.)
Thank you,
George