Keep onto the Police, ask the Chief Constable why you haven’t had a TF3, prosecutions for Road Traffic Accidents have to happen within 6 months of the accident.
Were there any witnesses other than yourselves?
IME, I was involved in a similar situation, had a busdriver who couldn’t give the number plate and as I was effectively the only witness. The Police managed to lose the 2 TF3s submitted so dropped the case – after the driver admitted he was driving the car.
Most importantly don’t get ranty with them, they’ll just drag their heels and so you were abusive towards them.