A resident of Ireland with a UK driving licence can exchange their UK licence for an Irish licence if they wish to drive in Ireland. However, to do so they must surrender their UK licence.
If a person wishes to retain their UK licence, they must go through the normal process of obtaining an Irish licence. This involves passing the driver theory test, obtaining a learner permit, completing the essential driver training and passing a driving test. It should be noted, however, that under EU legislation, an EU driving licence, including an Irish driving licence, can only be held by a person who is resident in the issuing member state and not by a person who is resident in a third country such as the UK.