What could be
Just the once? Can you have a plaque for every event? The Three Cups could have lots with Tolkien's name on.
For further information on how Swallow Hotels promote The Plough and Harrow, follow this link. I'm not sure that I would favour a "Tolkien Restaurant" in The Three Cups. The connection between Lyme Regis and the one of the world's most famous authors ought to be well enough known. If not, then a blue plaque for The Three Cups with Tolkien's name on it would be a very good idea.