I cannot believe that you didn't ask at the AFCO or at any stage of the recruitment process before you got this far down the line. It would have been far more discreet than 'outing' yourself in a public domain. You have been accepted you say and are now just a little concerned about what you are getting yourself in to and what others may think? Flabbergasted!
Obviously, it shouldn't matter in this day and age but with some you meet it will. The replies on here are testament to that. I honestly find it difficult to deal with homosexuals in general and not just at work. That is my issue to come to terms with and those that I do know are thankfully very discreet. You will just have to get on with it if being a blue suit Pilot is really what you want to be. Just do your best, pull your weight, don't look at using your sexuality as an excuse for why you are doing well/badly throughout training and keep your private life private.
However, now that you have announced on here that you are starting IOT soon then everyone on the next intake or two will be wondering which future pilot has the tag GP on PPRuNe. No doubt there will also be sweepstakes on the go as well.
As for luck......I think you will need lots of it
SA