Congratulations to your DD @Friendshipgroup, and to the choices she has!
In answer to your question re finance, there isn’t access unfortunately unless she’s in NI. There may be scholarships specific to history, but most will be for those from disadvantaged backgrounds. So it’s 3k€ tuition per year.
Re accommodation, there’s lots of movement between Round Offers. If she wasn’t offered Trinity Halls and on waitlist, keep engaged. Mine was in KC for last 2 years, last year’s fees for 38 weeks was 9,200€, most Yugo are similarly priced and they will have a mix of year groups in them.
The possible benefits to TCD, depending on her single/JH interests will be full access to Erasmus funding (DD’s history friends are all YA this 3rd year), if she wants it and academically qualifies.
If she’s bright and willing, there’s the Foundation Scholarship, available to all. It’s sat in Jan Y2, successful scholars get up to 5 years free tuition/accom/stipend etc for their Y3 to post grad studies. Massive saving if she’s awarded.
Re living costs, Dublin is expensive! But we were able to fund our DD £350 per month (exc phone) and she managed well, subsidised by her income from PT work. And she is a party type girl, and travelled a lot between UK unis/short breaks within budget.
Re your DD’s choice, it was a no brainer for mine, she was ready to leave the London crowd but the 2 semester calendar means they can be home from early May, flights into LHR/LGW are frequent.
The mix of student body is good, domestic/US and lots of Europeans wanting a EU English speaking UG experience post Brexit.
One final positive (I have rambled on!); DD sums up TCD by saying humanities students do not feel 2nd class there to STEM, business or medics as she feels some do at their UK unis. Anecdotal, but that’s her view. It’s not always rosy but overall, she has had no regrets.
DD will have saved on our funding her UG but it will come in substantially less than 4 years UK SF accrued, and Y3 abroad will be £ low due to geography of both semesters, Erasmus funding and subject related scholarships.
Good luck to your DD on deciding! Keep UCL offer until all is finalised, if TCD is her first choice, I.e. accommodation secured and paid for.