2001 Volkswagen Polo Car accident

Today was my first day of driving as I have just past my test and somehow (very stupidly) I managed to go into the back of another car, this happened in traffic at around 10mph if less, the damage to my car at first seemed bad as there was smoke/steam coming from the right hand side (driver side) from under the bonnet, this went as soon as I turned the engine off.

I then got out to find the cars tow hook (vaxuhall zafira) which was quite large had hooked inside through my grill into my radiator. The radiator was leaking fluid and is definitely needing to be replaced, however the damage doesn't seem to have spread to other parts of the engine. When starting the car again there was a loud rattling noise which went as I drove off (I had to drive off the road to a side road). I was wondering what this noise could be, and how much I should expect to pay for the repair of the vehicle. Thanks