Welcome! Echoing previous posters and as someone who thought 'great, I have a big 33x13 space, I'll model Connolly and surrounds and RPSI sheds, and then maybe Kildare, or a cement depot and a viaduct, gotta have one of those, and and and and....
What ended up happening was 'bits' of it were built, but it never really got beyond a loop before frustration, time demands and 'where do I even begin' sink in, resulting in me likely losing the interest of my two eldest in the process.
I now have a nice little 8x4 or so, with scenery, that my youngest participates in, while I dream of the 'big' layout maybe when I'm retired
Unless you have a significant budget and NO OTHER demands on your time, start small is my recommendation too
Hope that helps!