I think one of the most important things to be learned from the SOC is that, as it has always been, it is a guide only. So when your therapist (or other health professional) mandates that you must live a year (or longer) in your true gender before you can get on HRT*, ask why. If your therapist (or other health professional) makes any demands not supported or suggested by the SOC, you should find out why if s/he has not already explained his/her actions. And if your therapist (or other health professional) causes you to continually question his/her motives... maybe it's time to find another one.
Luckily, most often...a therapist experienced in gender identity issues understands all this and the biggest thing a person has to contend with is whether there is a good patient/therapist relationship.
If you are going to brave the trip with a therapist who is not experienced, but is willing to feel his/her way along the path with you, then you should probably know the SOC inside and out, or at least learn along with the therapist.
*Unfortunately, there is probably no getting around this in the UK.
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Let there be light...and blind the unenlightenable! -DML/2006
"Each of us has a deep need to be witnessed by others for whom we are. Each of us wants to see ourselves mirrored in others' eyes as we see ourselves." - Aaron H. Devor, Ph.D.
Time change serves no one except those who have nothing better to do with their time. -DML/2012