Thanks so much everyone for your thoughts. It's great to able to tap into a forum full of interested and helpful people - awesome! In answer to your questions, yes, we are currently sorting out fencing - we are fencing off a corner of our yard with a 5 ft wire fence so that if we are both out, we have somewhere to put the dog that it will be secure and we know it can't get out. And yes, I have had a dog before - 2 german shepherds, which were great, but my living situation was quite different then.
As far as which breed goes, that is a tough one. I was thinking medium sized and we both love border collies, but figure they are working dogs and really need to be kept active all day, which we just can't do (ditto for kelpies). My partner likes JRTs, but I'm not sure if being terriers they are prone to being a bit yappy ... any JRT owners out there who can comment?
I think it is very good advice for us to find a local rescuer, then ask them to advise us based on our situation and needs (can anyone tell me how to find 'Cazstaff'?) Thanks again for your help