There is an advance notice for a LH turn:-
Find local businesses, view maps and get driving directions in Google Maps.
and similar for a RH turn.
So one could consider the signage 'adequate'.
There may possibly be a 'technical' appeal based on Redbridge mismanagement of the enforcement process. This is usually their web pages for paying and appealing. Hippocrates may post to suggest something, so wait a while, but don't miss the pay/appeal deadline on the PCN. Such appeals are inevitably dealt with at London Tribunals with the full PCN penalty in play, but that is all, there are no additional costs whatever.
