Technically, if you crossed the white line, you committed an offence.
However, red light cameras usually take two photo's,
1 to show you crossing the line and the 2nd to show you carried on.
The law says, you should only stop as the lights change if it is safe to do so and won't cause an accident,
although I'm assuming it was on red as you stopped so they could argue that you are guilty of driving without due care and attention.
I'm assuming you only realised the light was on red at the last minute?
If you get a ticket, you could appeal on the grounds that you were stopped in traffic and then the lights changed so you didn't proceed maybe?
The photo's will show you didn't cross the junction so you should be OK.
it may be that if you were far enough back or (as you did an emergency stop) the car behind you was very close to you when the camera flashed in which case your registration number may have been obscured from the view of the camera.
You are just going to have to wait and see if anything arrives through the post but if you don't carry on across the junction you will probably be lucky.
Hope that helps