If you aren’t injured you don’t need to report it, give him a call and tell him to pay up, if he says no ask him for his insurance details at which point he’ll likely either pay up or refuse to give u details. If he refuses call the bill coz afaik he must give you insurance details. I got hit, minor damage, the guy took a while to pay up, needed a few reminders but did eventually cough up.
On the other hand if you are covered by your own insurance and think he is unlikely to pay you’ll need to report it and get a ref number for your insurance co. Trouble is then he’s likely to be as difficult as possible and try to deny liability. Tricky one. I got hit by someone who didn’t stop and my insurance paid up pronto (thankyou CIS) but the police haven’t managed to collar the guy (he wasn’t the registered keeper) so likely I wont get my excess back and my premium may go up next year