Congratulations on making your decision!
I'm glad to hear that you're excited about it!
Unfortunately, I can't really give you the answer to that question.
All you can do is ask your doctors, "I'm on this medication, can I use T?" and "Can I transition without T?"
I don't know about legal aspects, but I know that the hottest man in Canada is a transman who doesn't use T (No, seriously, it was in a magazine)
Plus, I know guys who don't take T who've had their legal sex change - with no surgery, mind you. I don't know if you'll be able to get top surgery if you're not on T.