Do the businesses there accept Master charge cards? I was told EE is the best SIM card?
I was in Scotland for three weeks last year and used my MasterCard and Visa both, and never had any problems getting them accepted. The only card you might have a problem with occasionally is American Express.
Master card and Visa are widely accepted (including in Skye). Apple pay is also common. American Express is rare in Skye as the commission rates are so high. As far as I know only the COOP supermarket and a couple of the high end restaurants take it.
EE is by far the best coverage in Skye as they have the emergency services contract.