You can still go to the police as, although they won't be interested in the accident as such, it is still an offence for this 'kid' to fail to provide his insurance details. There is no guarantee that the police would take any action, but they may be able to trace whether the kid had any insurance if you know the full reg no of his bike. On the basis of your description of the incident I doubt whether he was insured , however if he was then you would be able to contact his insurers direct in an effort to get your money back..
His failure to pay for repairs is a civil matter and the police would not be interested in getting you your money . If he is uninsured, you are left with the choice of either pursuing him through the Small Claims Court or making a claim through the MIB. (
http://www.miic.org.uk)
Either way, I suspect you have a long battle ahead of you with no guarantee that you'll get all your money back.