Hey, first of all congrats on both.
There are alot of things to factor In when choosing medical schools including your future. Do you want to work in Ireland or the UK?
Working in Ireland as an international after completing your 5 yrs is wishful thinking Imo. Although there are rumors of HSE increasing the internship spots there is still no guarantee that you will get one. I applied to Ireland as well and when I asked the dean during a Q&A session, she blatantly said that there's no guarantee that i will get to do my internship there. Last year due to corona all international graduates got internship spots but then were sacked as the cases went down. That's a major risk that you have to be aware of before deciding. You will need to give exams for UK or USMLE if you ant to go to US, which again is extremely difficult and there's no guarantee. You should also check of RCSI is recognised in your home country and/or you have to give any further exams as in my home country I'll have to give a set of stupidly tough exams if I study from Ireland but can easily practice if I graduated from UK.
Going to Uclan, you'll atleast be guaranteed a job in the UK provided to do well in med school. That is the major reason why most people end up rejecting Ireland and only apply as a safety and accept it in worst case scenarios.
Secondly, Irish colleges are extremely expensive for internationals, even more than UK colleges and aren't really that worth the money as far as what I've heard from my friends. Also RCSI being in Dublin is going to cost you a hell lot for accommodation and living expenses etc. Whereas Preston isn't that expensive.
Lastly, the facilities and expertise of UK schools is really good. The exposure you get in the UK is also pretty good. But Ireland is no less too. Dublin is a place you'll get alot of exposure and the medical facilities of RCSI are pretty impressive.
Lastly and most importantly, which country would you rather spend the next 5 and so years in? As ecolier always says, study in the country you want to work in. Although, working in Ireland as an international is very very hard, you could still give it a shot if you're really passionate about it. But again as an international, you must also see how easy it is to go back to your own country as well.
RCSI is well recognised but again, that shouldn't be something you must place your decision entirely upon as Uclan, despite being a new school is doing surprisingly well as far as the guardian rankings are concerned.
Both uclan and RCSI are extremely good schools. But there are alot of things you must consider. If I were in your place I would undoubtedly choose uclan, but don't let my decision influence you. Just follow your heart.