I have been chosen for a fully funded 4-years PhD at trinity College, Dublin. I am very happy to be the selected candidate, however I have some major concerns. The first one being the cost of living. I have already lived in shared apartments for the past 5/6 years and I would like to have at least the possibility to choose between a shared and a studio apartment at this point in my life, but I am afraid that, with a 19k annual salary, I will barely afford a shared room in Dublin. Anyone has any knowledge about the cost of living in Dublin as a PhD student?
Another concern is the 4 years duration instead of the "classic" 3 years project, which doesn't sound as a big difference, but I am from Italy and I am a little preoccupied about the distance and the "jump in the dark" (e.g., do i like the city? Can i live there for 4 years? Etc.) of such long commitment, which would not be a big concern for a shorter abroad experience as the ones I already had (6months, 2+ years).
At the same time, I am 28 years old with a master degree in evolutionary biology and 2+ years of research experience, and I wonder how long it will take me to get another successful PhD application.
Any insight or honest advice is very welcome, thank you.

Jump into the PHD if you are excited about the project. You made no comment on the project.

A Phd pays a stipend, very poorly compared to an actual job. You may have to continue sharing with another roommate for years to come or still have very little savings.

If you are wanting a very comfortable life, please don’t choose a PhD because you can’t get that during your study. Get a job and work your way up. There is nothing wrong with turning down a PhD. I assume you are concerned about your age since you stated that you are 28. When you graduated your non-PhD peers will have been seniors in their jobs with financial security while you just start out. If you are ok with this, continue with the PhD.