RLE is not required before starting HRT. I was on HRT for three months before I began RLE.
Unless you can afford to go totally private, you will want to go through OHIP. All the provincial health plans require following the WPATH guidelines, which call for an evaluation by a "qualified mental health professional". That can be a psychiatrist, a psychologist or a social worker, provided they have received the WPATH training. With a referral letter from them, you can see a doctor for a prescription.
Any medical doctor can prescribe any medication, but most GPs will avoid prescribing HRT, since they do not have the expertise to monitor levels. An endocrinologist can do it, or a GP who has received training.
I got my letter from a psychologist that I hired out of pocket (though my wife's insurance reinbursed me), to avoid long waiting lists in the public system. I get my prescriptions from a GP within the provincial (NS) health plan who specializes in treating trans clients and has enough training to monitor low-risk patients on HRT.
