Failure To Stop / Driving Without Due Care or Attention

[mambo^]

Basically i have a got a letter through the post saying that when i went shopping last week, when i parked my vehicle i scrated another vehicle in the carpark and a witness reported me. I did not know this until yesterday when i received a call from the police, and upon taking a closer look at my car i have got a small scratch on the back wheel arch.
I have been driving under a year and havent put a foot wrong anywhere else.
they say i could get a ban and a fin, aswel as paying my insurance excess.
does anyone have any idea what the implications of all this could be?