Ok, were the police called ? Does the fact that he didn't stop at the scene of an accident count for anything ? What car was he driving ? What damage was done to his ? The police can estimate the situation given the damage to your car and where it happened. From one point of view it simply looks like you saw too cars coming, thought "I can make that" and went for it, but was too slow and got hit side onwards.

The flip side is the guy approaching the roundabout thought "fuck this, i'm round this cunt" and overtaked into the side of you on the roundabout. Hindsight is a wonderful thing after an inncident, but there's a lot of people on the round with a complete lack of driving sense.