Depression, anxiety, stress ect

Depression’s really awful, I’ve suffered from it for a long time - funnily enough, most of it was caused by a rubbish upbringing (won’t go into details) and being ground down in jobs I hated.
A few months ago, I quit work to try being self employed as I was doing okay with my side business (was and still am fully registered with HMRC), but struggled with money so tried a part-time job again. The plan was to get a few hours a week to bring in the rent, then work hard on the business in the meantime. That’s the van driving I’m doing now. I was so happy when I was fully self-employed, despite the money worries, and yet I started loving the driving, too.
But work want me, in fact are able to force me as I stupidly signed the contract with this clause in it - to go and do retail work in the store. The thought of dealing with their weird till system, trying to flog financial products and upsell stuff to meet targets and KPIs, and deal with customers for hours on end, brought on a panic attack and the depression kicked in big time earlier this week. This evening has been pretty bad. Shame I was enjoying the van driving and looking forward to moving onto better driving jobs after some experience, but this has put the mockers on it because I can’t face shop floor work. I’ll probably resign, I have no choice, I won’t last if I’m put on the shop floor. That’s my ambition to train for a C licence put on the back burner, as I’ll need my savings to survive until I can get another part time job (business not bringing in enough to keep me fully afloat, trying hard though).
So I’m not trying for sympathy, I’m just stuck again, and I’ve been in worse situations, but this is where the triggers start going off, and no-one can help me but myself. But it’s rubbish while it lasts. And I think it’s that feeling of utter helplessness that can push someone under; when you’ve got virtually no support network (no family, rubbish GP, etc) it can easily get overwhelming. A long time ago I nearly checked out completely, yet from the outside looking in, you’d never have known.