Not yet, I'm actually in the process of applying for SSI and it's looking bad.
I have an ADHD + GAD diagnosis, the psychiatrist that interviewed me agreed but said this is hard to get SSI for.
I know you said you're in the UK, so I really don't know about AS and the disability system there, but in the US, I do know that some autistic individuals are automatically approved and rarely have to through an appeal process.
Otherwise, it's very difficult. MANY people are denied, there's an appeal process and lots are then approved with a lawyer's help.
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AD/HD BAP.
HDTV...
Whatever.