[LlamaLlamaDuck]

Any "disability" I have would be mental health related and at this point, I've been told I have 3 different types/severities of depression, likely schizophrenia (but apparently I was meant to get over that when I was 17), serious paranoia, and social anxiety. None were actual diagnoses I don't think, so no one knows what's up with me.
I've only ever mentioned it on an application for a college course and that was so they'd be able to set me up with a support worker in the college and I'd be able to get help from them if I needed it.
In terms of work, my current employers know nothing about my health in that sense and apart from being pretty jumpy at times, it's never caused a problem.

If anything were to get worse in future and it would affect me work/require some accommodation then I'd mention it then.
If it doesn't cause any problems with your ability to work, then don't mention it if you don't want to. As far as I know, the only thing you have to mention by law is anything on your criminal record.