Do you know with what offence you have been charged?
There are two offences under the Public Order Act which may fit the bill. Section 5 offences are generally entitled �Public Disorder�. The more serious Section 4A offences are shown as �Disorderly Behaviour with intent to cause Harassment, Alarm or Distress�.
The less serious attracts a maximum penalty of a fine of �1,000. Alternatively (and only very rarely) a Community Rehabilitation (i.e. probation) or Curfew Order can be imposed. The magistrates� guidelines suggest a starting point of a fine of one week�s income.
The more serious carries a maximum penalty of six months imprisonment, but the guidelines suggest a starting point of a Community Penalty.
From the way you describe this incident it seems to be at the lower end of the scale of seriousness and this, coupled with your previous good record should enable their Worships to reduce their sentence from their starting point.
As with all offences, if you plead guilty at the earliest opportunity, you will receive a considerably lighter sentence.