Songs about travelling people surely do apply, perhaps some songs about feeing, and songs about the Scottish Highland clearances (Robin Williamson's "Return no more" is a beautiful though recently written example for the last mentioned).
Traveller's songs, i.e. songs collected from travellers' singing, many of them of course about being homeless, can be found in:
E.MacColl, P. Seeger, Traveller's songs from England and Scotland, Univ. of Tennessee Press, 1977
P. Kennedy, Ed., Folksongs of Britain and Ireland, Chapter: Songs of the travelling people.

Martin Ryan has mentioned "Blue tar road". I'll post it in a separate thread.
Wolfgang