I'd be careful here.
If you were entering the carriageway and the other car was already on it, and you collided, then that is legally your fault.
The responsibility for judging the speed of existing traffic and assessing a safe point to join the carriageway is down to the joining driver, so even if the other car was speeding, that probably cannot be proved, but the impct points on both vehicles will prove that you were legally at fault.
Approach the other driver, and tell him you are prepared to accept a 'knockl for knock' solution to avoid involving insurance companies, and hope he doesn't press the issue, because it may well be that he has the rightful damage claim, and not you.