Publishing is difficult because it is hard to find publishers who will do it for you. The Writers and Artists Yearbook (should be available through your library) will give you advice on finding a publisher or if you decide to go down the route of self-publishing.
Because your book is of interest to a specific area, it is probably going to be hard to find a publisher because your market is going to be so small - unless you can find a publisher that carries small, local interest books. So you are probably looking at self-publishing. There are two routes to self-publishing. One is that you order a load of books from a company that will print it for you, so you take delivery of hundreds of copies of your book and then try to sell them, or you use a print on demand company.
You could use a company like AuthorsOnline (
www.authorsonline.co.uk) which runs a print on demand service. Print on demand means you - or your local bookshop, if they want your book - can order small amounts, so that way you don't end up with a load of surplus books stuffed in the attic! They will also list it on the usual book lists so that it appears on online sellers such as Amazon.
But be warned, publishing is not easy. I actually used AuthorsOnline for my own book in 2007 and my book does sell regularly on Amazon. However, every month I see the sales figures for other books that have been self-published and very few do actually sell. Interestingly, it is the ones that are of peculiar interest that sell better than, say, general fiction. So because yours is a specialist interest it might do better. But it would be up to you to work at your publicity, so try to get a book-signing with a local shop, a reading at your local library etc.
Hope that helps! Good luck!
Louise