About Autism Diagnosis Adult Diagnosis Is seeing my GP the only option? There are many professionals and organisations that can provide private assessments for you. People sometimes opt for these as waiting times can sometimes be lengthy, however costs do vary.It’s also important to note that some local authorities may not accept the results of private diagnoses. They might insist upon an NHS diagnosis before they will provide services to you. For this reason, we suggest that you stay on the waiting list for an NHS assessment even if you do decide to go private.