I was wondering this, I thought the discrimination was about disability, particularly, and "depression and social anxiety" are casually considered illnesses rather than disabilities.
https://www.gov.uk/reasonable-adjustments-for-disabled-worke... says "Employers must make reasonable adjustments to make sure workers with disabilities, or physical or mental health conditions, aren’t substantially disadvantaged when doing their jobs."
and the examples given on the gov.uk site include a specific mention of an anxiety disorder "doing things another way, such as allowing someone with social anxiety disorder to have their own desk instead of hot-desking"
But I don't know where "reasonable adjustments" comes in with this. "I have social anxiety and don't want to present in front of a group, may I send an email instead" sounds reasonable to me. "I don't want to send an email, someone else will have to do this part of the job" doesn't sound reasonable. You don't reasonably hire one person to do a job, then hire another person to the parts the first person cannot do, right? But I'm no lawyer.