I'm very sorry you had a wallop. It is never nice. Don't let it put you off riding. These things happen, but rarely.
I'm afraid i found your description of events impossible to understand, but my impression after reading it a few times is that you were following the car you hit.
That being so, the fault would lie with you. You need to allow room for the vehicle in front to stop suddenly.
As to why the driver didn't give details, I'm not sure speculation is helpful.
Yes, he may not have been on the road legally. Equally, he may have considered it a minor issue and wanted to be on his way. Your injuries may not have been apparent to him. Some road users might see a sore hip and a grazed elbow as 'not real injuries'. I'm not saying that myself, but some might.
If the scenario is as I imagine it (you hit him) then I am dubious about going to the Police and saying "I was at fault in a collision and the other driver didn't give me his details".
If you are OK and the bicycle is OK, I'd learn the lesson (which I imagine you already have) and hop back on the bike.
Some will disagree with me on that. It's just one view among many. Follow the guidance that suits you best.