You might be able to get historic mapping from envirocheck, a product from the Landmark Information Group;
You can buy old OS maps from Cassini;
Or try local libraries and historic collections. You will probably have to photocopy or scan old maps and georectify them yourself but there should be extensive collections. British Library and Public Records Office (PRO) at Kew both have loads of old maps.
British Waterways or UKHO might have some old maps of navigable channels.
Good luck, let me know how you get on.