I can also recommend the Tubal Cain books. At SMEE we use his Polly design from book 1 as the basis for our Polly course which has been very successful.
It introduces most of the metalwork skills a model engineer uses – using hand tools, soft and silver soldering, turning, thread cutting etc. It does not use castings so mistakes are cheap.
We diverge from the book to some extent – we prefer to use seamless copper tube for the boiler and put three bushes in the boiler (steam outlet, safety valve and filler).
You may save some money by using 42mm plumbers tube for the boiler instead of 1 3/4 inch but will need to adjust the engine stand design slightly.
Roger Woollett