37mph in a 30mph speed change average speed camera

I was going on a dual carriageway A3220, London from a roundabout when a car was steering into my lane and I honked at him. This made my adrenaline go up. I got onto the dual carriageway which is 40mph. It then changed to 30mph after a bridge and there was a SPECS average speed camera and I was doing 37mph not realising it had changed, because I was looking in my rear view mirror, until later in the day I checked on google maps and my dashcam.

Will I get a ticket for speeding in one average speed camera?? And I’m I able to fight it? i’m a new driver and this ticket would remove my licence but Im a bus driver and this would mean i would have no job.