The NRM. or Railway Museum as they have decided to drop the National, do have a number of layouts on permanent display. They did, a year or two back, contact me about putting on the York Model Railway Show at the Museum. Minor problem was that they did not have a spare 3,000 sq Metres that we need for the show! The other major problem is that layouts need to be seen operating and therefore need operators. This can cause problems during weekdays but possible on weekends perhaps.
There are many Model Railway Shows around the Country most weekends. They are well promoted to Railway Modellers but not so well to the general public. The problem here is one of cost. Even an advert in the local paper will set a club back £500 or more, and it may not generate sufficient increase in numbers through the door to cover the cost!
Press Releases are useful and often picked up by the local press and even radio and TV, but and a big BUT they need to be well written and must relate to a local story. Not the easiest thing in the world to do. But worth a try.
Peter