The Church of the Welsh Martyrs is your nearest Catholic Church and is located in Penparcau on the edge of town. (as seen in the map below).
It is roughly 1 mile from the Town Centre and Penglais Campus. If you need transport to get there please see here: http://www.parishofaberystwyth.org.uk/parish-bus/
Address: Piercefield Lane, Aberystwyth, SY23 1RX