How much do it take to get dismissed?

I’ve worked for a major bank in a call centre environment for the past 18 months, which is my first ‘real’ job post university. I’ve always been a top performer, been recognised as colleague of the month etc. However, my manager went off on long term sick and the temporary one has been much stricter on call marking. I’ve failed two calls in the past month for misinformation (due to lack of clarity in policy, one caused customer harm, one was just feedback and was fixed with an email), so I’m now on a development plan where I get regular call checks.

I was initially fine with this, but think I may have given misinformation out on Thursday, and worry there will be a complaint when I return to work. I didn’t intentionally do this, but it has been very busy lately for the department and I didn’t realise until after the call ended they were Scotland based, which changes the legalities of the situation and what I had told them quite confidently. I don’t know if I should wait and see if a complaint does come in — I know it won’t be picked up since a call already had been marked that week — or try to rectify by giving the manager a heads up about the situation. The latter usually would be my go to, but the temporary manager has been very difficult to deal with, and has already caused me to (rather embarrassingly) cry in office after shouting at me for the previous mistakes.

I’ve been informed if I fail the plan then HR will be involved. I have diagnosed anxiety which I’ve never disclosed to work as I never want to make excuses but the whole weekend I have been feeling sick and not sleeping at the thought of what will happen, and I can’t shut off due to the fear of this.

How much does it actually take for someone to get fired for this type of thing, or have you witnessed many firings in your time? We are incredibly busy and understaffed which I’m hoping means I have a chance of getting through this period, but I’m equally terrified of losing my job when I have rent to pay. I’m of course looking elsewhere, but given the current market, I’m not sure how long this will take.