I've used the Aviva service a couple of times - old battery was dead and they fitted a new battery; another time an alternator(serpentine) belt went and replacement was fitted.
In both cases I just had to pay for the part, the labour costs were covered, and they were able to fit it in the driveway.
The car was at home at the time, I was waiting a few hours for them to come out but understandable as I wasn't an emergency case.
Possibly AA would have faster response times, especially in remoter areas.
You can see the full T&Cs of the Aviva cover via this link, scroll to page #26:
http://www.aviva.ie/media-library/MotorCare-Policy-Booklet.pdf