Is your boyfriend insured to drive a vehicle under the 'extension to drive another vehicle' under his own policy? If he has one? If not, your insurer is liable and they could come after you for the losses they have incurred as a result of your boyfriend's negligence. What you must do is report your boyfriend to the police for taking the vehicle without your consent. Otherwise, you may be liable. It is an offence to "knowingly allow a person the use of your vehicle if they are not insured". This means you can be prosecuted if you do not report him.