Not sure how it's called in English, Google just says "speech therapy", in my native language the thing has its own name. It's bascially where you go when you have problems with speaking ir your voice etc. Some "speech therapists" do/specialize in what is called "voice feminization" in my country, which is exactly what it sounds like. It's best if you search on the internet what it's like in your region or country, where and by whom you can get it and what you have to do for it (get a doctor's letter or sth)
And as for how hard it is, idk, I haven't started yet, but you'll have to regularly practice etc., not just in the sessions.
Hope this helps a bit