This basically what you put on the appeal form.
“Obviously you just appeal online like the PCN tells you on the back.
Do not say you forgot. Say you have cognitive difficulties and can’t recall the incident or why the operative would not have seen your Blue Badge, which you do display normally. And here’s a picture of it (photo redacted for personal data privacy) and you hope they will make a ‘reasonable adjustment’ for your case and cancel the PCN.”