We sign post a lot to various people and I highly recommend two EP's
1. Batul at CF Pyschology
https://www.cfpsychology.co.uk/ - they charge around £750 for a full assessment
2. Dr Joesephine Storek -specialises in ASD,ADHD and giftedness but assesses the full range
http://www.thekensingtonpractice.com/
Do take your time to choose the right person as you can not undertake the tests for another 18 months once carried out, so it's worth waiting for the right person
Elaine