I think you should re submit asap. I read in another thread a guy resubmitted his application in the same situation and it was accepted. You are not considered over stayed till 28 days after you visa expiry. That's what solicitors say but I couldn't find this information in the home office website....

I posted my application within three weeks ov visa expiry - on UKBA's advice I waited in order to have the most up-to-date bank statement information. But I was in a rush and sent the wrong photos. Instead of calling me, they refused my application as invalid and returned it, but my current HSMP has...