I can't help myself, I just couldn't let go. So I did some more research (and after this I really stop).
Ofcourse there is the well-known city of Sofiya in Bulgaria. And also the spelling of this name is very common in Russia, especially in Ukrainia. But the pronounciation of your surname made me think of the old English pronounciation of Sophia (see my previous message). Therefore I think it is best to start from there.
I found out that there are 1.661 people in Great-Britain with the surname Sofiya, a number of them live in the county of Clackmannanshire, where Sofiya is the 36th surname.
You can find more information on the website of Sofeminine. I give you the URL:http://surname.sofeminine.co.uk/w/surnames/surname-sofiya.html