From experience (last September) I can tell you that you should go to the hospital and explain what happened and ask for a check up also see your doctor and get a prescription for pain killers , Your insurance company will sort out your car as it seems that as you were hit from behind this was not your fault, as far as claiming is concerned check your car insurance and see if you have legal cover if you have then your insurance company will put you in touch with a firm of solicitors who will take the case up for you, if you are not covered by this then you will have to find a firm that will take this matter up for you, keep all receipts for pain killers, physio treatment etc as these will be required by the solicitors acting for the other driver before any payment is made .As far as compensation is concerned it is a claim and this will be sorted out by your by the solicitors.Trust this helps.