Replacing garden gate: permission needed?

Hello

A first time post - grateful for you advice. I am a leaseholder looking to replace the the ageing gate that goes out onto the communal block the flat is on. I've looked at the Southwark repairs page and see that this seems to be the leaseholder's responsibility.

Do I need to get Southwark Council's permission to change this? I can't find the information on the pages. Nor can I tell if it is a 'standard' gate, that would need to be replaced like with like (and if so, where to get one?).

Thanks in advance.