There are Adult Education classes that are given free of charge for (ESOL) English as a second language for Adults. I have a link for the adult education center in Houston: http://www.hcde-texas.org/default.aspx?name=AdultEducation
They have advanced English classes That can help you with Vocabulary, Fluency, Idioms, and all that you are asking for in a class. They do have evening classes at various locations. I suggest reading the link I gave you and checking into these classes. The nice part is most of these classes are free of charge.