Congatulations, A songwriters dream come true. In the U.S. the poormans copyright has been used for years, how successfully I don't know. My understanding is that Odetta may have come up with this plan. Actually I think oyu need to mail the song(s) registered with a postmark stamped on the song itself and a postmark over the glued edges of the flap. Keep it safe in a vault. Sandy will probably have an easier and saner way of doing this but then it probably costs moneyand we folkies barely can afford the stamps.
Ireland and Great Britain ( actually, I heard recently its just Pretty Good Britain now) may have laws that don't allow forsuch things. Call a legal aid society.