There is going to be a festival near where I live which is open to the GLBQ community, and is advertised as such.
I have only ever heard of GLBT and so not familiar with this other term.  Does this mean it is not open to transgender people? So basically I am also asking, what does the term Queer mean and what does it cover?

I was under the impression it meant 'anything else not entirely mainstream'. 
I'm sure they wouldn't raise any objections to you going, at any rate!