"No landing fees at Fair Isle or indeed most of the other small islands."
False.
Contrary to the fees list on the Fair Isle web page the landing fee is now £20 and will be gleefully pocketed by the NT for Scotland Warden.
Similarly on Foula which has even fewer facilities the fee is £20.
You must absolutely not interfere with the sacred Islander flights on any of the islands served by them. The risk management / duty of care / health and safety / hi vis jacket / ppr / basic service morons have seen to that...
The best places to visit are Sollas beach (free) or Lamb Holm.