Not far away from Mount Pleasant Airport is Bertha's Beach. There is a webpage falklandislands.com, you can find the contactinformation and they give you the payment information. They have a wise account, so you could use IBAN. Or you could pay at the bank. But the banking hour at Standard Chartered is from 9:00 to 14:00.
You get a code to open the gate and you can drive to the parking lot.