Tranarchy in the UK: Questions about GRC and immigration

cross-posted from: https://lemmy.dbzer0.com/post/31696866

I am a cisgender man with dual citizenship between the USA and the UK. My husband is a transgender man who does not have UK citizenship.

As part of our threat modeling, we are developing a shortlist of nations where we would migrate if things get rough. The UK, while being on a worrisome trend line with regards ro trans rights, made the list because it would be relatively simple for us to move and work there with my citizenship already sorted.

Could any UK trans people help us to understand the GRC? My husband has fully transitioned with respect to his US documentation. When we married, he was also a man. Since all his documents match, could he get by without a GRC, or would he be forced through the humiliation of immigrating as his birth-sex and then acquiring a GRC once we moved? Would a GRC be necessary to receive basic healthcare and/or hormones?