Hi Brooker.
In a similar situation at moment.Would probably say mine is slightly worse than yours.Over aggressive bouncer punches my brother - I lose it and hit him 3 or 4 times.Glassin my hand - 2 small cuts on his head. Like you I regret it and just wished I had walked away.
I am in magistrates tomorrow for it to be committed to Crown Court.This is firstly because CPS deemed it serious enough for Crown and secondly my solicitor advised a no plea at this stage as I would lose all credit and could just be sent to jail by magistrate without much case knowledge. I would class it as 50-50 for jail but I did use a weapon and I think this is the factor that could send me away.I like you have no record,family,kids etc.
A big factor is how premeditated it was - by the sounds of it it wasnt on your part and I would say self defense is your argument.In my case I am awaiting for the commital and going from there. Look at my own post for advise I have had which may apply to yourself to an extent!