Appealing grades based on learning disability?

Basically, I was recently diagnosed with ADHD. I've "known" something was wrong for a while now, but passed it off as chronic laziness. Anyhow, for my GCSEs I didn't try very hard so I didn't do well but for my AS's I worked my ass off and I know I haven't done well. Since the diagnosis came round after the examination period, is there any chance to appeal and maybe get leniency?

any help would be appreciated!

(also, I know ADHD isn't a learning disability quite so explicitly but you don't know how **** never being able to focus is until you're never able to focus).