Currently AU libraries, the National Library of Wales and the Aberystwyth Research Portal, receive from AU academic departments:
All successful research theses
and also stock pre 2013 Taught Master’s:
theses on a Welsh subject
theses achieving a distinction
Further information: https://www.aber.ac.uk/en/is/library-services/collections/theses/
Aberystwyth has a theses collection which can be useful when you come to write your own. They are all on Primo, if you want to search for theses on a particular topic use the keyword thesis along with any other relevant keywords.