My Thai wife entered RoI on a British visa got stamped in at Dublin Ferry Port arrived from Holyhead Port in Uk.. no problems. Check first on the Irish government website to see if any changes have been made recently.
I told DWP where I was living abroad and they froze the amount of my state pension from that date, I was worried that if they found out and I hadn't told them I would loose the lot.
I have a UK Natwest account with a Thai address and phone number pension money goes in there and I transfer monthly through Wise (formally Transferwise) into my Bangkok Bank account..no problems and have been doing this for 6 years. I use online banking from start to finish and usually get my money same day and within 6 hours.