Shouldn't sa nGearmáin be accepted as well?
It seems like i can't get the use of 'san' and 'i' right. When do i use which?
sa is used for i an. Most countries are definite (the five big ones which aren't: Canada, Ireland, Scotland, England, America), so they'll all generally be sa. san occurs before a vowel sound.
Thanks a lot for clarifying this!