I understand your frustration seemster! Most schools don’t finish until 3.30pm so you would think you could drive as normal along a local street before this time but alas no. Once the school streets have been set in motion by Southwark Labour then I’m afraid there’s nothing you can do and sadly I would say to you to pay the fine. The Dulwich Village system is the same since it started and people living and driving as normal have been bombarded with the local Labour councillors’ ideas and regulations and carers and family members are affected.
I’m in the process of appealing a PCN at the Morrison’s car park in Camberwell at the moment and awaiting a reply. I have proof I paid at the ticket machine so that’s the only reason I’m appealing.