Diagnosis etc. - NHS Funding Query

I am hoping that someone can answer my question about the procedures for NHS funding for diagnosis (and for post-diagnosis counselling).

I saw my NHS GP in August to try to get referred to the Adult Autism Diagnosis service in Sheffield.  She was very sympathetic and was happy to refer me, but she told me that it was impossible to get funding for Sheffield (I am in Derbyshire).  She told me that they have tried many times before and that it was completely impossible.

A friend saw a different GP at the same practice at about the same time and he was instantly referred to Sheffield. 

How does this work?  The doctor who referred my friend is a more senior doctor so perhaps that is something to do with it?  I don't know.

I eventually got a private diagnosis, because the NHS wait in Derbyshire is 2 years and my mother is 78 and is the only person who could answer questions about my early childhood (which I thought was vital, but it turned out that it wasn't).

I am going to try to get some post-diagnostic counselling which I know that you can get at Sheffield.  I have booked an appointment with my friend's doctor!  I'm not looking forward to it, as I suspect that I will be refused.