>>567188Where are you from then OP
I hiked trough a good part of the Highlands in Iceland 2 years ago.
As long as you keep to the lowlands as on your route, everything is fine, just prepare for the worst possible weather and steep prices. Besides Reykjavik and possibly Akureyri there are no big cities, so if you need special gear, get it there. Camping is easy, camping grounds are plentiful and wild camping is no problem whatsoever. Hot springs are everywhere, so bring your trunks.
If you want to go to the highlands, thats a whole different matter, arctic desert, no people, no shops, rudimentary jeep tracks, no bridges, lots of rivers, lots of fords, and the volcanic ash / dust will eat your moving parts alive, stuff ate my boots in no time, abrasive like nothing else. Let me know if you need more info on the Highlands.