I had exactly the same thing happen to me 2 years ago, articulated lorry hit my van and drove off....police did nothing and weren't as interested as i thought they might be as to what i classed as a hit and run lol!
Cut a long story short i had to claim on my own insurance as the lorry company wouldn't admit liability (i traced the lorry myself rememebring what was on the trailer and making some phone calls to the company etc), driver claimed he didn't know he'd hit anything which seemed to absolve im of any responsibility......literally 2 months ago i finally recieved a cheque for just the £300 excess i had to pay after it was passed onto solicitors etc.
No compensation for the fact my insurance more than doubled the following year after making that claim, as well as putting my car insurance up to as i'd made a claim on another policy....what a load of rubbish!