Free Traffic Legal Advice

Hi everyone, directed here from Reddit and it seems like a great resource!
In April of this year I was clocked doing 110mph on the M6 between junction 15-14. I plead guilty as the photo was accurate and I'd confirmed that the camera had been recently calibrated, I don't feel like I can dispute the charge. Due to the amount over the limit I was, it's been escalated to a court appearance on the 17th December.
I can't really afford legal help and I'm curious about what I should prepare for the day.