Beaumont Society seem to have a section for 'transgender youth' on their site, now. Perhaps undergoing a bit of a rebrand?
Oddly, there is a section for 'MtF' but I could see nothing for 'FtM' and nothing for 'non-binary'.
Male to Female (MTF)
MTF people are assigned male at birth, but wish to present as female on either a temporary or permanent basis, depending upon the degree of their dysphoria.
'Typically, this group of the gender spectrum tend to be more visible in society, where they are often referred to as trans-women, transgender women or transwomen. Here in the Beaumont Society, we advocate that the label transgender shouldn’t be confused with that of transsexual. Although this definition is by no means universally accepted, we support parliament’s use of the term transgender, considering it as an umbrella term that includes all types of gender variant people (See 2015 Commons Select Committee report).'
I can't make head or tail of that paragraph, frankly.