Sounds to me like you do have ideas. Good ones.
People helping will need a bit more exacting info though, How big is the room?, Do you own track, turnouts, etc.?, Scale detail, or Post War style? Will you need help in the carpentry/cabinet making, or just track detail. Even your locos style/brand and stock lengths, they have overhang, and kick-out in curves. Can they climb a grade well?
Also there are a lot of programs for track design that are downright fun to play with once you get the hang of them. I play with two free ones for windows. Anyrail5, has a 50pc limit for free version, and SCARM who author happens to be posting here https://ogrforum.com/t...ello-from-the-author