Ahhhhhh?

fiveforfive - collective fund for trans women and girls and transfem causes

gendered intelligence - trans led advocacy org

mermaids - supports trans youth

akt - lgbtq youth homelessness charity

loving me - domestic abuse service for trans people in england

Trans Aid Cymru - supporting trans people in wales

Queer Emporium - hub of queer businesses and events

And ones who operate in Wales but also across the UK

TIN Wadrobe - supplying clothes for trans and gnc people

Scottish Trans - Trans advocacy, information and social events. Run by the Equality Network, a broader Scottish LGBTQI advocacy group.

LEAP Sports Scotland - Sports charity that advocates for queer inclusion in sports, runs trans sports groups (Trans Active) in at least Glasgow and Edinburgh that I can absolutely recommend.

LGBT Health & Wellbeing - Not trans specific but includes trans specific, trans led and trans inclusive support and social events, and supports a variety of smaller community-run subgroups.

And another couple UK-wide:

Gender Identity Research & Education Society - Trans led charity supporting research on trans matters and education/training on trans inclusion. Does consultancy for public and private sector organisations.