Solo 1st time visit - looking for recommendations!

I bit the bullet and booked myself the trip I've always wanted - and I am going solo as I couldn't find anyone able to join me. I am visiting Iceland on my way to see a friend in Serbia, and will stay in Iceland Nov 5 - Nov 8/9 (flexible). I fly in to Reykjavik (arriving 0600 on the 5th), and intend to do an airbnb so as to meet some locals hopefully. That said, I am considering a 3 day tour (http://www.tourradar.com/t/92440#months=november-2017) to see as much as I can during my short stay. I wanted to see if anyone had experience/opinions to share? It isn't a cheap tour, so I appreciate any and all input!

Thanks in advance!