Technically yes - they often say ignorance is not an excuse (no offence intended), so the fact that your friend did not have insurance when he said he did is going to be on your head for not checking rather than taking his word on it.
I see this a lot dealing with claims - very rarely I see the police doing anything about it to the person who lent the car.
You should expect an IN12 (I belive) conviction on your licence which is allowing someone to drive without insurance- prob carries 6 pts and a fine