Just been arrested and charged for section 4 (1) public order what happens?

Hello last night whilst waiting in a Que for a club some bloke pushed me i went and spoke to him not in a manner for section 4 public order. i then returned to the que he walks over and smacks me, being shocked and dazed i walked over 10 seconds later and hit him whilst he was being restrained by a bouncer, i was then arrested and in a cell for 12?? hours i was then charged section 4 (1) and (4) public order act. i have to go to magistrates court, its my first offense and worried i be locked up, Im 30 and a law abiding citizen i do have a caution thou for ault when i got hit by a bike other then that im clean.. is it prison for me? thou looking at the cctv it doesn't look much..