court case for not having permis de construire

[Woodlands]

Help!

I have just received a Citation a Prevenu Devant le Tribunal Correctionnel for not having a Permis de Construire for a yoga deck we built in good faith - with the verbal permission of our local mayor, who it turns out did not give us the correct advice. Long, boring story... Basically what I want to know is, what is the likely outcome of such a court hearing? Will I be slapped with a fine of a few hundred or a few thousand Euros? Has anyone had to go through this procedure? I know nothing of the French court system. Is there a French equivalent of the Citizens Advice Bureau or some other organisation I can contact for advice (my French is good)?

Thanks.