Welcome aboard!
Although the Railwire is perhaps best known as a cadre of exceptional N scale modelers, there are a growing number of us working in HOn3 like you. My main modeling effort is a 12 x 14 foot (imperial units of course!) HOn3 model of the Rio Grande Southern, with my secondary layout being an N scale caricature of the standard-gauge Colorado Midland Railway.
I know you've been in HOn3 for a very long time, but I have to mention that if you're getting a layout going and not looking to hand-lay your track, check out Peco's line of North American HOn3 track. Their Unifrog turnouts are about the best thing going. The vast majority of turnouts I'm using on the RGS are Peco #5s. Hopefully you can find them in the UK since they're
made there, LOL. Also, Blackstone's engines are getting ever harder to find, but you will never have a better-running locomotive than a Blackstone C-19 or K-27. Time was I could pick them up for around $400 US, but those days are mostly behind us.
Still, there are lots of exciting things happening in HOn3 these days, including the resurrection of the Grandt Line product line by San Juan Models. 3D printing has made the lesser-known narrow gauge roads easier to model as well. All-in-all it's a great time to be in HOn3.
We look forward to seeing your layout take shape! May I also recommend that you start a thread in our Layout Engineering Report forum?
https://www.therailwire.net/forum/index.php?board=20.0You can share progress, solicit inputs, socialize design and techniques, and document the thing start to finish.