H.C.
Some of the local firehouses have rooms that you can rent. Also King Farm has a community room, I don't know if you have to live there, but you can also try them. I know that they let the City of Rockville use for classes, etc. The website for the community is www.kingfarm.org, I believe the contact info for renting the room should on the website.
Good Luck!
H. C