There is very little on the web in ‘Irish’ for weddings of a religious nature and even less of a non-religious nature.
But if it’s of any help I do have 14 page PDF document containing Blessings/Toasts (not all religious), Prayers and scripture for Weddings that I put together after doing a few days of online research. The document does contains a short-list of online sites and references from which I drew my material from. Everything in the document is give in Irish, English and phonetically. (Phonetics could do with a proof-reading by me…to be done over Christmas).
For non-religious material such as a poem you could consult one of the many fine poetry books in Irish.