I and a few of my family serve in the RAF. One of them recently "outed" himself as he thought he needed to let us all know but he was worried about our reaction. Most of us responded with "we already knew; you can dance and have fashion sense!" He was quite relieved that the response was just "banter".
I also work with a young lady who is in a civil partnership. Other than finding out through her arrival interview, she doesn't discuss her partner or sexuality any more or less than her heterosexual colleagues.
The point is, let people find out through getting to know you rather than announcing it, particularly out of the blue or in new company. Many wont care either way unless you have already tried to make it an issue. In that case, as a previous poster mentioned, it becomes about your personality rather than sexuality.