How do I broach the subject of referral with partner?

Hi there I'm new. I was diagnosed with adult combined adhd last year. More recently and as my adhd meds have started working and I've been unmasking more I've become more aware of traits that aren't really explained by ADHD. 

I've had a few people comment they think I might be autistic who are also thinking that for themselves and seeking diagnosis. As I followed a lot of adhd and ND accounts I was seeing a lot of things that fit how I feel but are described as Autism not ADHD.

I did a few online tests and then when I had an appointment with my psychiatrist on Tuesday I asked her if I should get an assessment. She sent me a screening test to Complete and said I showed significant signs of being autistic and would write to my GP to refer me. 

So. I have told my best friend. My sister. Work (as they are giving me reasonable adjustments for adhd and I have help from access to work). 

But not my husband. The reason being that since I've become more aware of autism I am pretty sure he may be autistic (possibly also adhd) too. He was pretty dismissive when I told him I was getting referred for adhd. 

When I mentioned to my sister a few months ago "I think husband might be autistic". She looked at me and said "er yeah he definitely is". Her ex husband is autistic and had picked up on things from my husband. 

It would certainly explain a lot. And a lot for me too. 

So how do I tell my husband I am being referred for assessment but also I think he'd benefit from an assessment too? I don't think he even realises himself, and has been masking his whole life, especially at work where he is calm and professional. Meeting people outside of work he appears rude and even I feel like he's rude and blunt with me but since becoming aware I'm giving him more leeway and trying not to get upset when he's like it with me, because I know I can appear the same. 

Well done if you got to the end of that, over explainer, moi?