In which case I would seriously advise starting with something a LOT smaller, a little layout that you can learn the skills of woodwork, track laying, ballasting, wiring, scenics, all the things that go together to build a layout. Even just an 8ftx4ft single board with a couple of ovals and some sidings, something to play trains on!
The reason I suggest this is that if you've not built a layout before then something very large and ambitious has a good chance of being too much, and you may find you've bitten off more than you can chew and you may get ten percent of the way into it and lose the motivation as it's such a long journey. It also gives you a good chance to explore what parts of model railways really appeal, are you a layout builder, an operator, a wiring and electrics enthusiast, a main line driver, a shunter, a signaller?
For layout planning you really can't beat trying things out on a computer first before you commit to timber and track, it's well worth the small (relatively) amount of time it takes to learn your way around one of the computer layout planning programmes. There are several free programmes out there, Ravensclyffe was planned on XtrackCAD https://sourceforge.net/projects/xtrkcad-fork/
It may also be worth investigating whether there are any model railway clubs where you are, they can be great places to learn the basic skills you will need.
Good Luck!
Andi