Welcome aboard. I was in a similar situation. I grew up with relatives working on both the Milwaukee Road and Northern Pacific, and was lucky enough to spend numerous hours riding in the cab of steam, diesel and electric locomotives. I had a small HO layout going and the left Montana when I joined the Navy. No room for a layout on a destroyer. After 6 years active service, I stayed in Florida where I was stationed and built a small 6' x 3' N scale layout. At least I had something. It was small enough to slide under a bed. I finally moved home to Montana and built a house, making sure that it was on a basement. I incorporated my small layout into a fairly good sixe layout, with 16 scale miles of main line in N scale. Unfortunately, this was in the 70's, and the quality of N scale locomotives were what I would call marginal at the time. I also couldn't find the road names I wanted in N scale.
I ended up ripping everything out and move to HO scale. 20 years later I am still working on it, slowly trying to improve things. Over time, my skills improved, and this opened doors to building a better layout.
Building your diorama is a great idea. You can possibly incorporate it into a layout at a later date. You can learn a lot her on the forum. Don't hesitate to ask any questions either. I'm sure you'll be able to find out what you need here.
