Once you get to Contin you are on the main road all the way. This is a fast and busy road at ferry time. All those caravans, campervans and lorries rushing to catch the ferry.
Not awful, but a single carriageway with, at times, 80mph tafiic can be interesting. From just after Loch Glascarnoch it is pretty much downhill all the way.
as has been mentioned you can get a train to Garve, or there should be the bike bus running in the summer which will take you all the way, D&E Coaches run it.