I have been collating various autism related web addresses and came across an autism section on the website for the Royal College of General Practitioners (RCGP).
For some reason, there are two web addresses for the same information:http://www.rcgp.org.uk/clinical-and-research/clinical-resources/autistic-spectrum-disorder.aspxhttp://www.rcgp.org.uk/ASD
I was surprised by the amount of useful information available. The 'Autistic Spectrum Disorders Toolkit' web page (http://www.rcgp.org.uk/clinical-and-research/toolkits/asd-toolkit.aspx) is particularly informative; to highlight just two examples, the page includes a link to take you to the relevant text of ICD-10 (Version: 2016) and has a section for autism in females.
There is a guide for GP reception staff (http://www.rcgp.org.uk/clinical-and-research/toolkits/-/media/60663BF35A1F43ADBAC65E108B8518EC.ashx) that includes possible reasonable adjustments. There is also a 'Making the most of a visit to your GP' guide (http://www.rcgp.org.uk/clinical-and-research/~/~/media/Files/CIRC/Autism/RCGP-Making-the-most-of-a-visit-to-your-GP-Jan-15.ashx) which also includes possible reasonable adjustments.
It is a shame that the RCGP use the word 'Disorder' rather than 'Condition' but that does not take away from the information provided.
I did not find anything similar when I searched the General Dental Council (https://www.gdc-uk.org/) or British Dental Association (https://www.bda.org/). If I missed the information, hopefully someone else will post the links.
NAS has a web page (with other links) relating to dental care and autism:http://www.autism.org.uk/professionals/health-workers/dentists-info.aspx
Based on a very quick read, Scottish Autism has a similar web page:https://www.scottishautism.org/services-support/support-families/information-resources/visiting-dentist
This Nature article is on my reading list and it may contain some helpful information:http://www.nature.com/vital/journal/v9/n4/full/vital1570.html
Assuming I have not missed the information on the General Dental Council website, it is a poor show that they do not have something similar to the RCGP.