What happened when I got knocked off a long time ago (by a SMIDSY coming out of a pub car park at 9am) when I was a total newb (no camera etc) was that the guy gave me a mobile phone number (which was correct) and then drove off because I said I was okay and was considering continuing to ride in but this was just the adrenaline turns out I needed stitches and a trip to A&E he could probably have seen the blood everywhere but whatever. When I called the mobile phone number later that day he answered but as soon as I said who I was he hung up, I went to police to report and asked if they could do something to trace the driver, I had witnesses and the mobile phone number but not the reg. They refused to track him down based on the mobile phone number saying it wasn't a serious enough incident. Luckily I came off a bit worse than the bike which apart from a few scuffs was fine, helmet and gloves etc were a write off though.
So lesson learned, always get the reg and insurance details, if you are hurt get the police don't let them drive off, get witnesses and get a camera incase there are no witnesses coming forward or they hate cyclists.