Get some authors involved - the more famous, the better. Once you have, then get on to the press and let them know who's coming. In fact, any local celebrity could lend weight to what you're doing.
Your best bet would be to contact individual authors via their websites and explain what's happening.
Also, have you lobbied your MP?
Good luck - we've been in a similar situation. We had three small branches close last year. Borrowers from one are still campaigning to get it reinstated even though our lease expired on the building six months ago!