Perhaps I should have worded my comment better. By asking what offence had been committed I was suggesting that it was not a serious enough matter for the Police to want to get involved. Particularly these days when they are having to deal with more with diminishing resources.
I believe that the obligation in the event of an accident is to EXCHANGE details with the other party - something you cannot do if they are not there. (I don't think that there is anything laid down in respect of the other party being absent - is there?) Although mosty of us would be considerate enough to leave a note there are those that do not.
If the details of the vehicle are known then this can be followed up via an insurance claim. After all, the desired result is to get the bike repaired.
One final thought. I would not assume that the driver drove off deliberately. In an LGV it is quite possible to hit a parked bike and not even know it.
Let your insurance company do all the chasing - after all, that's what you pay them for.