Playing catch-up. Here we go.
The thing is that you don't have to MOVE before COPR expires, you just have to show up in Canada. You can leave on the next flight out. I would suggest that you stop faffing with trying to get COPR extended as it's highly unlikely that you will be extended, and you instead just get your husband to book an overnight trip there and back to activate the COPR. With your medical expiring on 3 July and with COPR being issued in May, CIC will see that as plenty of time for you to book a flight, particularly as you would have known beforehand that it was extremely likely that your COPR would only be valid until 3 July - it's no secret that COPR is only valid for one year from medicals.
So I'd suggest you just get a flight booked, get COPR activated, then come back tot he UK to sort out your affairs. Your husband can travel on his own to activate COPR, you don't have to be with him.
Sorry to sound harsh, but you don't want to mess around with it, just get something booked and get it out of the way, save yourself the stress.