Hiya Lucy and welcome to Susan's from another UK resident.
If you are going through the NHS then things are a little inflexible, though thankfully not as medieval as 2 years RLE before treatment. if you go private then I think things are more flexible but can't say first hand as I don' t have that kind of money.
So far as the NHS are concerned, if you are in Scotland then the options available to you are really quite enlightened - Google can find you the details. I am in Wales so can't comment from first hand experience again. I will share my experience so far, which I think is reasonably indicative of what to expect.
I started part-time back in April last year. Though to be completely honest I was wearing androgynous clothing, clear mascara (Boot's natural range) and clear nail varnish to start with. I slowly slipped in to a more explicitly female presentation as I felt comfortable with each step. A little light eye shadow, brown mascara, a touch of foundation, an obvious feminine top - you get the idea.
I went to see my GP back in June last year. My GP referred me on to the local mental health services where a consultant psychiatrist (September) quizzed me for half an hour before referring me on to a gender specialist (February this year). The specialist checked me over to make sure there was nothing else going on and asked me to go full time (including a name change) and come back 3 months later. I saw the gender specialist again in early June having fulfilled her conditions and was given a clean bill of non-insanity and a referral to an endocrinologist.
I remember being roughly where you are now about 17 months ago and it was a really scary and daunting place to be so you have my sympathies. Little steps in the right direction one after the other worked for me.
Love,
Rosie.