Am I reliant on the council classing this as a genuine mistake on my behalf and my first time appealing this type of contravention?
Not totally. You recognised your error, and reversed out. Yes, you passed the sign, but if I were an adjudicator, I'd put this down as
de minimis. Trouble is you'll have to risk the full PCN to get an unbiased opinion. All the council are interested in is your mone
Are there any grounds of defence due to the amount of time that has elapsed between the date of contravention and the date/arrival of the notice?
Nope. They have 28 days from contravention date to serve a PCN.
In the absence of PCN errors and errors in the traffic order establishing the restriction, all you've got is
de minimis unless the others can come up with something.As you have to submit reps and get a refusal so you can go to London Tribunals, why not submit reps on the basis that as you passed the sign you realised you had made an error, so immediately backed-out. Post up their inevitable rejection when you get it. It's this or cough-up.