I am confused
You say ( avoiding the quote police) The TomTom showed 30 and the speedo showed 35
So the speedo is showing a speed "higher" than the TomTom
If that is correct then by following your speedo indicated speed you would be Under the speed limit.
Q. Were you entering a 30 limit?
Q. Was the camera forwards facing?
Q. if both answers were yes then were you at or below the limit when you reached the "30 sign"?
Confession time
It happened to me. As I approached a 30 limit I backed off rather than brake. Thus I entered the 30 at about 37 and was down to 29 when I passed the "nasty white van". I was given a ticket for 37 mph and took the option of a naughty driver's course.
The course taught me some valuable lessons and I believed then, and still do now, that it was well worth the fee and these course should be available without first getting a ticket. I also met there some of the most stupid people who are allowed to drive. Their level of ignorance about the road, and rules of the road were such that I find it difficult to believe anyone could be so daft.
Since then I have been the slow old bloke who will not exceed a 20, 30,40 or 50 limit no matter how much hooting and flashing I get from behind.