[1][2] Brennan was born in Dublin and was raised in County Tipperary where she attended schools in Clonmel and Thurles.

[1][3] She studied English and Latin at University College Dublin, then undertaking a Higher Diploma in Education.

[14] Her poetry is included in The Great Book of Ireland,[15] The Field Day Anthology of Irish Writing, Volume 5,[16] Eating her Wedding Dress (Ragged Sky Press, 2009),[17] Catullus Gaelach, edited by Pádraig Ó Laighin (Coiscéim, 2010),[18] and is widely anthologised.

[19] Her two collections of short fiction were published as An Banana Bean Sí agus Scéalta Eile (Coiscéim, 2009) and Staying Thin for Daddy (Arlen House, 2014).

She was also a founder member of Comhaltas Ceoltóirí Éireann in Carlow, serving as chair and secretary.