Ah, Pebble Island.
The Island is quite big and trekking around on foot can take some time. a very good contact there is:
Mr Raymond Evans
Pebble Island
Falkland Islands
He's a very helpful man and is used to pointing and helping enthusiasts in the right direction. He's got a Land Rover but remember that Benny Benz is expensive.
Most of East Falkland is accessible by Land Rover and you can hire one in Stanley. Don't waste your time trying to borrow one from BFFI as there aren't enough assets to cover HM's business adequately. Accessibility West of Goose Green can be challenging. As far as the Islands are concerned, HELO is the only practical option for the ones not served by FIGAS. Although not much use without diving, if you want to get to the crash locations in Choisaul Sound, make friendly contact with STO(N)FI who operates from JFLU in MPA. Don't let the Austral Winter put you off that time. There are many days when the WX is clear but breezy. Summer is when all the goofers and other assorted rubber necks choose to visit. They are generally a pain in the bum. Also, "out of season", you would have better asset availability and a greater supply of good-will.
Good luck.