Mark Hi Catherine,
I just came across your page and thought that I would reply to your post.
I am contemplating a coast to coast trek across the interior of Iceland next August and have spent the last few months looking into the logistics of doing this. My current thinking is that I will start in the south at Skogar or Porsmork, walk to Landmannalauger and then follow F26 to Nyidalur. Looking to finish walking and hire a bike at Reykjahlid before cycling to Akureyi on the last day. Dates and route still flexible but I am looking to finalise this shortly so that I can book the flight up before the fares go up. At the moment looking to arrive in Reykjavik on Thursday 11th Aug and fly back to the UK on Sunday 28th Aug. Will walk an average of 26km (15 miles) a day. I plan to camp during the entire crossing and plan to send 1-2 resupply parcels to a couple of huts e.g. Nyidalur before the trip to minimise pack weight. Still have detailed route planning to do.
I love backpacking and have walked across Scotland twice now as part of the TGO Challenge (http://challenge.tgomagazine.co.uk/challenge/) and wish to broaden my horizons with this trek. Although I would attempt this solo I will feel happier sharing the experience with someone, or a small group of like minded people. Let me know if this aligns with your thinking.