My commiserations.
If you're hit by an uninsured, unlicensed driver, the chances are that if not stolen, the car isn't registered to the current 'owner', and/or doesn't relate to the plates on it.
In the event of a collision, I suggest that you offer some form of photo ID with proof of address and ask the other driver to do the same. If they say they can't, call the police saying you suspect the driver is uninsured and if appropriate not licensed or impaired. Photos aren't of any real use unless the driver is well-known to the local police.
It saves a load of hassle to keep a copy of your Insurance Certificate in the car - it's of no use to anyone else - but don't EVER leave the V5 Registration in the car!
When you sell a car, the law is that YOU MUST fill out the V5, getting the buyer to provide evidence of identity and address. You may not take payment in cash for more than £10,000
Guy