Hey Matt!
Well done on talking to your doctor mate - I bet you feel great now
I didn't chase up my doctor at all, and it took him months to find out where to refer me etc. I did, however, have to go and see him on a completely different matter, and while I was there he actually mentioned that he hadn't forgotten about me and was still chasing it up. After that, I didn't really feel I could hassle him too much about it.
I guess I'd leave it a month or so, and then ask them where they were up to. However, having said that, it's probably unlikely that you'd receive a letter or anything within that timescale, even if they refer you today! Is there any chance you'll have to see her about anything else in a few weeks and can casually drop it into conversation then, to make it less like you're hassling her? You want to keep them on your side, after all, as they're the ones who'll be writing your T prescriptions and doing your blood tests etc eventually
Keep us posted anyway mate!
Dave