The right to choose option for assessment

Can anyopne explain what this looks like, practically, I mean, ie do I ask the GP to do this? Do they have to have these agreements in place with other places? Is there any way I can find out what agreements they have in place with who? it's not on there website so I guess it means asking. Do you need a reason to choose another place? or is just being faster a good one.....Is the DSM 5 criteria usually used or others? which is best suited to woman. Does it matter? 

I'm on the NHS waiting list (about a year in my area). I hope to move and don't want to then have to start again at the bottom in a different area.. 

I've read the information on here and other places online so I'm not looking for that. Sorry about all the questions, thanks for your replies. 

God bless you all