IF you choose to strike out on your own from Reykjavik by car ALWAYS take supplies. The ring road is good for driving but food and gas are limited and stores, repair places and the like very few. Blanket, water, some simple nutritious foodstuffs, phone battery charger/backup. Just the first ideas. It can be a lonely and scary experience to be on a road with traffic so far apart.
Also take the local weather advisories seriously. High winds can be more than you have ever experienced. Iceland is a large ship of land in the vast North Atlantic. We were there in Mid September so mostly out of main tourist season. Perhaps summer has less risk but BE alert.
