Early autism symptoms 18 months

Hi there,

I wanted to ask for some advice about getting an assessment for autism for my 18 month old son. He’s beginning to show some of the symptoms of early autism such as fixed attention on things like opening and closing doors, turning light switches on and off and stiffening his legs when he is over excited or stressed. He also doesn’t have any words yet and is mainly babbling. How would I go about having him assessed? I’m aware early assessment is quite important to support with intervention and so am keen to get some advice. Anyone else in a similar position at all?