Hamburg is a good city, I lived there for nearly six years in an area called Altona, sharing a flat with my GF and a German girl and a Polish/English girl. I know some girls that lived in Frankfurt working at an Amercan base, As to where you come from the UK is still a member of the EU and it depends on the outcome of Brexit if you will able to claim permanent residancy after that. For trans people Hamburg is a comforatable place to live.