Hello John and welcome. You'll find lots of locomotiveers on here.
2 things that can help:
1) Give your approximate location so that persons who may be be able to help can see you in person and,
2) Join a local model engineering society, especially if contemplating boilermaking. The regulations have changed over the years and a local boiler inspector can be very useful. Also, most clubs have a tracksite so you can have go at driving with the help of someone knowledgable and, when you have finished an engine you will have somewhere to run it.
All the best with your plans and remember, this is a good place for advice and help.
Brian