How shall I explain my 2:2?

I have finally secured a training contract interview with a small City firm. However, I’m worried about the interviewer asking me to explain why I only got 2:2 in my contract law module?

The honest explanation is that my tutor was terrible and quite a lot of the other students in my group also mucked up. Do you think the interviewer would view this as a bad workman blaming his tools?