i had a similar incident in a car park in my astra, i turned into a side road of an asda supermarket to park, and some guy in his rav4 drove into the side of my car, not fast at all, but it still needed a new door skin and some repair work, he tried to blame me, saying that i was racing my friends around the car park trying to race to a space (how stupid does that sound?) and that i skidded into the front of his car, to do that i would have had to handbrake turned into his bullbars! there wasn't even any damage on his car, suffice to say he did not want to pay the excess on my car (£350) so i took him to court, around a month before we were due in, he offered 50% of the excess, i said no. 2 weeks before he offered 75% i said no, my dad said to take the money, but i knew that i hadn't done anything wrong so still said no, and with just a week to go he offered 100% and complete liability.
the thing you need to do is take as many pictures as possible, as soon as possible. you may have seen that somebody drove into my P&J recently, and i was so shaken up (not from the crash just that my car was shagged) that i didnt think to, but talking to my dad he said to take loads of photos. luckily i did and i think they help somewhat and would help a great deal if it were ever to go to court.
also again sorry for thread highjack, and i hope that you get it sorted. seems a lot of people are having accidents recently, my count is around 4 me, you, the guy in his cup, and that guy who had someone pull out on him, but had been drinking the night before so wasn't covered? something along those lines.