trains

You don't say what era your train dio is but if its 30's - 40's then the airfix RAF rescue set will be ok . That is 1/72 scale but will mix in easily with 1/76. There are lots of model buildings for railways but they are in card, plastic or plaster so you need to decide what will best suit your project. Try getting a Model Railway magazine and look through cos they have loads in there and lots of companys that do mail order.

i'm from northern Ireland land of nearly no model shops so i might have 2 buy of the net

Give Langley models a try : http://www.langleymodels.co.uk/ There a hundreds of locomotives in 1/87 (HO), but the difference between it and 1/76 is very noticable so I wouldn't go there. There's plenty in 1/76.

revell has a 1/87 locomotive.

Your post doesn't say where you are located, but in the US any Modle Railroad shop will have everything you need. If you can do mail order, go to Walther's site; they specialize in model RR fixtures and accessories in all scales. Good luck in your search.

1:76 is the OO scale used in England. It is still reasonably popular there so you should have no problem buying buildings, vehicles, etc. from dealers who specialize in it. A quick web search should bring up dealers.