Nyorai kuenderera mberi kweiyi ndima - Brennan akaziviswa semumwe wevatsva vatsva kuNigel Carolan's Connacht academy pamberi pemwaka wa2015 / 16. Kutamira kuConnacht academy kwakamuonawo achidzokera kuGalwegians padanho repamusoro, achitamba rugby yevechidiki yekirabhu. Mumwaka wake wekutanga muchikoro ichi, Brennan airatidzira nguva dzose kuGalwegians muAll-Ireland League uye akatambawo kuConnacht Eagles, chikamu chechipiri chepurovhinzi. Akatanga kudzidziswa nechikwata chekutanga uye akatumidzwa zita muchikwata chevakuru kekutanga ku2015 <unk> 16 Pro12
mutambo neUlster musi wa1 Kubvumbi 2016, kunyangwe iye asina kuratidzwa kubva pabhenji. Brennan akanga ari mumwe wevatambi vana vechikoro avo vakadzidzira naConnacht munguva yemwaka pasina kuwana cap yechikwata chevakuru. Apo chikwata chakakwanisa kuenda kumakwikwi ekupedzisira ePro12, zvisinei, vamwe vese vechikwata vakabhadhara kuti vauye nevatambi vana kumutambo muEdinburgh mukucherechedza mupiro wavo.