Your insurance company will bring your rates up for three years following most HTA convictions.
As for the sign not being bilingual, this has consistently proven to be the "default" strategy for fighting "disobey sign" in many parts of Ontario. I'd do the leg work before your attempt to plea bargain with the Crown, meaning set up your trial date, then make a full disclosure request.
See if they give you proper disclosure. The prohibited turn sign, in this case, was put in place by a by-law. As weird as it sounds, if they do not provide you a certified copy of the by-law that erects the sign as part of the disclosure package (part of the "explanation and clarification of the charge") that is sufficient to get the proceedings quashed. The other things you should receive are the officer's notes (typed please).
Take a photograph of the sign with a time-date stamp on it. Bring your evidence with you to court, if the proceedings don't get stayed. Then, in court cite the French Language Services Act (section 5), the fact that Toronto is a designated bilingual region (therefore communications such as the sign must be bilingual), and Ontario Regulation 615 (which gives examples of bilingual signs). The sign that indicated what you did was illegal was itself not in compliance with both the FLSA and O.Reg 615, therefore of no force and effect. The JP should dismiss the charge at that point. If the JP does not, cite the R. v Myers case. So you've got plan A, B, and C: Plea-bargain to municipal; quash on improper disclosure; bilingual defence. Hopefully it works!
For more information on bilingual defence and how to make it work, check out this link:
http://www.ticketcombat.com/step5/bilingual.php