Stats (demographics) required

You can find some stats from the Autism Self-Assessment Framework responses last submitted by local authorities two years ago:
https://www.gov.uk/government/publications/autism-self-assessment-framework-exercise (big spreadsheet)

You will also find figures in the local Joint Strategic Needs Assessment, eg http://www.eastsussexjsna.org.uk/

In the 2017 school census there were 978 pupils in East Sussex recorded as having ASD: a rate of 13.3 per 1,000 pupils. This compares to a rate of 13.1 per 1,000 for the South East and 12.5 per 1,000 in England in 2017.

To find the total number coded as autistic on local GP registers within a certain age rage, you could ask someone on the Public Health teams (for both councils),

Hope that helps.

Just to clarify - is that how many primary school aged children are diagnosed with autism? Have you considered writing a Freedom of Information Act request to both West and East Sussex County Council requesting this information in a digestible format?

https://www.gov.uk/make-a-freedom-of-information-request