Hi Keiran,
An charge will only be "thrown out" if there is not enough evidence to prove your committed the offence. If the police have enough evidence showing you were disorderly in public, or that you refused to give details when you were required to at law, and they decide to pursue the charge in court, then you will be convicted.
However, if by "thrown out", you mean the judge (Magistrate) will give you a light sentence, such as a warning or fine, then yes, there is a possibility of this. This will depend on your individual circumstances, including circumstances of the offence, your conduct then and since, you criminal background, any character witnesses, you personal background etc.