I reckon I know which railway it is. 777 mentioned an ED, and then a 35. Well the Bentley miniature railway has both, with 2 5" and 7 1/4" 35s.
I second the advice of building to a deadline. Trust me its tricky. My 7 1/4" loco took me 2 years to build, then I tried to finish it within a month for an event at the acton railway. It was impossible, absolutely a lost cause, fortunately I was sensible enough to realise that the loco stood a chance of failing in traffic and backed down from the event so I could finish it properly.
and finish her properly I did....see her this weekend at the Acton Miniature Railway. Please excuse the smell of burning from under the hood
may I just say that I think 442s are great (mainly because they're front ends look like old SR units!) but what is the point in making dummy cars? Basically it sounds like your just simulating a Pig drag in miniature. It would be more exciting if it was powered. Come on, break out the Sinclair C5 motors!!!
but whatever, my China Rail QJ with the 6-axle tender requires some thought.....