neurological testing/brain scan for autism

Hi

I am fascinated by how the brain works. I read about Templin Grandin and how she had brain scans. I would love one to help me understand how my brain works. I have autistic traits diagnosed by a psychiatrist. I was diagnosed with dyslexia and dyspraxia by a psychologist.

I saw a video on social media who had a brain scan by a neurologist- He had adhd but learnt how his brain worked. I have enquired about getting a diagnosis by a brain scan. I had head injuries too from unsavoury parenting and falls.. Austism and learning difficulties run in my family. 

Anyone know how I can volunteer for studies or get a brain scan and a diagnosis in the uk/overseas?