KG11 Snow

Hi, I am a UK resident who started a job in Ireland in April 2024 (working remotely from the UK, visiting occasionally). At the moment I am paying Irish tax monthly (PAYE, universal social charge, social insurance), but have recently been advised by HMRC that I will also need to submit a self-assessment tax return in order to pay UK tax on my wage as it is classed as foreign income. However I thought that the UK and Ireland had a double taxation agreement - how do I activate this and which country should I be paying tax in? Thank you!