I've normally found the local JobCentre to be great for giving careers advice and support.
Go in, say you want to increase your hours/switch jobs/are struggling and would just like some help or pointers to local career services.
Careers services are normally super friendly and will have "seen it all". Be honest about your worries with anxiety and ND and MH. I think there's specialist disability employment advisors as well?
There's often courses and coaches who will talk you through things like doing a CV or applications, or they may know about volunteering opportunities available.
I didn't find they got me the perfect job, but just having a chat with someone helpful and friendly is a nice first step if you're feeling out of the mainstream.
You could just go in physically one day.
Keep posting here for support if you're anxious.
Socially, again I'd say baby steps.
Find one small free thing to do and go to it.
Even if you're not religious, a local spiritual group like the Quakers or Buddhist centre can be friendly and supportive and you turn up, sit with other people, have a cup of tea and go home.
If you're in X city, Google X Quakers or X Buddhist centre for the address.
There'll normally be a weekly meet which is free and open to newcomers.
You're not going to feel better immediately, but take one day at a time. Keep posting if you need to process or let your thoughts out.