The video confirms your account of the circumstances, and sorry to say, you have no valid case for the PCN to be cancelled. Your entry into the bus lane was too far back to be considered de minimis, I'm afraid. You should also note that unlike every other London council, Havering will not re-offer the discount when rejecting representations. On the other hand, it means anybody submitting reps to them that are rejected has no additional financial exposure when registering an appeal at London Tribunals, because the penalty remains the same, and there are no additional costs.
My view is that you don't have a case on the contravention, but others may suggest 'technical' appeals that have won in the past, so wait a bit, but don't miss the discount deadline if you're minded to pay.
