Heya folks. Thanks for all your answers. I've spoken to the SU president and LGBTQ+ officer. What I think I'll do is be openly trans, but not necessarily 'come out'. I'm going to have a flag up in my room, and I wear a pronoun+trans flag badge, plus I'm going to some protests/pride stuff the week I get there, so I might invite some people along to that if I make friends in time.
This is what I'm planning to do when I start teaching too (wear a pronoun badge and have a couple LGBTQ+ flags in a pen pot), so I think it makes sense to try it now.
I'll be totally openly trans within the LGBTQ+ soc too.