Historical Reference Book Publishers

Hi been researching for a long time, and have hit the publishers brick wall.
Have got what I feel is a rather good historical novel, come reference book.
It is just loaded with facts, and unknown documents and pictures, about a Dorset Victorian family.
Think Penguin or Harper Collind perfect for them, but they only take Literary Agents work, (less money for the author).
Can anyone help and suggest, yes have tried Self publishing, but just do not have the finances to allow the publicity.
Thanks for reading.