Tobytibbs you can not use self defence as mitigation here, you approached him , that makes a difference, it means that in the eyes of the law you are the aggressor (the one that started it) . My advice stands, plead guilty and apologize to the court and to the man you hit . I can not see you getting more than a fine and community service if you do as I say.
Just to add , why did you think the CCTV would clear you? from what you tell us it would show you starting the fight by approaching the other man, it would prove your guilt not clear you.