Any idea which dialect? Would I be more likely to hear "fy hun" or "fy hunan" in South Wales?
I think it's "fy hunan" which more common amongst the southern dialects, but really just learn both and use which ever one you prefer. I use both depending on whichever one fits best into a sentence.
I've seen "hunan" used in my school textbooks, which teach "south" Welsh (i went to school in the welsh valleys)