First step is to write to the guy.
My suggestion:
1. Outline the incident that led to the damage.
2. Write that you hold the driver liable.
3. Ask for damages and specify the amount, backed up with a copy of the relevant invoice(s).
4. Set a deadline for a response.
5. Announce that you will take direct action through the courts if he fails to respond.
6. Write that you are happy to arrange settlement through his insurance if he prefers.
Check
http://www.hmcourts-...laims/index.htm for more details and the online claim route - it's an easy process to pursue for small claims, it's cheap, and it's actually quite entertaining and educational to see how the courts work in such cases should the driver decide to defend his case.
When the amounts involved are small, a DIY court action is an option. Do it online. No need for lawyers, and it works reasonably fast.