Gires- http://gires.org.uk/ — has many free online trainings for GPs and other professionals on their website
All of these are fantastic to give to GPs especially if they are new to trating trans* patients or are resistant.
NHS guide to hormone therapy- PDF- http://www.gires.org.uk/assets/DOH-Assets/pdf/doh-hormone-therapy.pdf
Wpath standards of care-PDF- http://www.wpath.org/uploaded_files/140/files/Standards%20of%20Care,%20V7%20Full%20Book.pdf
Good practice guidelines for the assessment and treatment of adults with gender dysphoria-PDF-https://drive.google.com/viewerng/viewer?url=http://www.rcpsych.ac.uk/files/pdfversion/CR181.pdf
Interim protocol for gender identity services