English teacher from England. Currently teaching in South East Asia.
Schools should have LGBT policies in place, not all do. This programme is a few years old, from Teacher’s TV, but is a good look at being a gay teacher http://www.teachersmedia.co.uk/videos/gay-teachers I would be very surprised if you were the only gay teacher in your school
Every teacher should join a union, which will be free for you during your PGCE anyway, in fact you can join them all and take the goodie bag! I was told once that NUT offer better support to LGBTQ teachers, I’m not sure how true this is. I was a member of NASWT as I had a better relationship with their in school rep and I felt if I ever had a problem I’d feel more comfortable talking to him. The NUT website has a LGBT page that may be of use to you http://www.teachers.org.uk/lgbt