In addition to the educational info (which my employers pretty much ignored), I used the "Carry Letter" from my therapist to give myself some medical backing. It described my GID diagnosis, that I was under her care as well as a medical doctor, that I was to be treated as a female, that I was on HRT and intended to transition fully, etc.
I also wrote a short summary letter describing my intentions (to transition and live as a female, as Kate), rough timeline (HRT changes to expect, name change hearing, SRS, etc.) and list of my doctors (therapist, medical doctor administering HRT and laser doctor).
I wanted to make absolutely sure they understood how serious I was. In the end, they really only needed to know what I was doing and when, and they came up with their own plan on how best to integrate it all within the company's interests that was fair to everyone.
I'm not sure I understand where you said you changed your name at work... but haven't come out at work? Management should be the one changing your name, IMHO, and they should inform and insist that your cooworkers respect the change.
~Kate~