OP - Dr Maite Ferrin at Re:Cognition Health in London. Expert in ADHD, senior within CAMHS.
Aniesa Blore at Sensational Kids in London - you go down and get assessed there. She's in Surbiton.
Helen Pearson at kids-communication.co.uk in Sussex. She travels to you.
Aniesa's written a book, as a parent and OT, on being where you are, and working out next steps.
Ideally, no problems will be found. Look on it as akin to antenatal testing, where the aim and hope is that there are no issues, but if there are, it's important you know as early as possible.
If parents wait for problems to surface really strongly before they do all of this assessment, then by definition it is late intervention. Yet all the evidence is that early intervention is key. With my son, I found out I needed to do this much, much too late. With my daughter, I had her fully assessed at 6, when I knew there were issues, her lovely Yr 1 teacher agreed, and then we had the EHCP in place by the age of 7. Her mental health is much, much less of an issue than her poor brother's is.
Both my kids are exceptionally able. My son just got a 9 in his GCSE mock, and he's 13. He'd be in Yr 8 if he were in a school. My daughter has IQ results ranging from 96th to 99.98th centile. Yet both are autistic, both have ADHD, she has SPD, he's dyspraxic and with APD. They both have complex profiles they call 'spiky' and in both cases, they mask like absolute professionals.
Really good experts see past that. Early intervention and proper support is key. You can only get that with expert assessment.