After reading up your issue, I must say, that you must take your ticket to court and set a trail date. This way you can contest the ticket in court.
They will send you a trail date, and than you may research up on the left turn, and try to get a legal advice in depth.
So, in my opinion since this charge carries two demerit points, it will not really effect your insurance. This charge will stay on your abstract for three years from the date of conviction.
Now, if you chose to JUST pay the fine and call it a day, then do not worry too much, but if you need more information for trail date and the process, please post back with more questions.. THANK YOU.