Looking for an expert witness on trauma (eg psychiatrist)

Can anyone recommend to me a credible healthcare professional who could assess and diagnose my 12-year-old autistic daughter for trauma, anxiety and PTSD?

I guess I’m looking for a psychiatrist but could maybe be a clinical psychologist. I need someone with letters after their name who could be an expert witness at a SEND tribunal. 

We want our local education authority to understand that our daughter has been so traumatised by school that she needs an alternative educational provision - something that allows her to follow her interests and fulfil her potential in a safe, positive and suitable environment.

I need a credible expert witness who can meet our daughter and write a report to convince the tribunal that any school environment would be harmful to her mental health and her education and not in her best interests.

Any ideas? 

Thank you! We’re based in Macclesfield but would travel for the right person or open to working through a video call…