Ok. This is probably a Notice of Intended Prosecution then and unfortunately they are just in time to pursue the matter.

You will have to respond to the NIP. If you do not they will just charge you with failing to identify the driver which carries 6 poins and a fine.

They will send through a conditional fixed penalty offer probably of 3 points and a fine or the red light awareness course. The latter does depend whether its supported in your area but its likely to be available in most areas now.

There is the outside chance that they could prosecute you for driving without due care and attention instead which carries 9 points or potential disqualification but not on the facts you present above.

If you do not accept either the fixed penalty offer or the course then there is a chance that they will forget ot summons you. That does sometimes happen. They only have 6 months to lay an information and so they will be out of time fairly quickly. If they do forget to summons you then you will walk away with nothing. However, if they do remember then you would have to plead as you cannot deny the offence on your account. You can plead by post and you would still only get 6 points but you would face court costs and the victim surcharge as well.

Hope this helps. Please remember to rate my answer and then I will be able to carry on for free.