1. There are several banks to be found in Tobago including the First Citizens Bank, The Royal Bank of Canada,  Republic Bank of Trinidad & Tobago and Scotia Bank. The legal tender in Tobago is the Trinidad and Tobago or "TT" dollar. T&T has a floating exhcange rate between $6.29 - 6.30TTD to $1USD . The U.S Dollar is widely accepted and most businesses accept  them for obvious reasons. It is not easy to spend Sterling cash so you should exchange those currencies at the Bank.

BANKS NEAR THE AIRPORT -

Within the Airport compound (Crown Point International = now re-named ANR Robinson International) there is a Cambio, and one ATM machine of First Citizens bank in the car park.

A short distance outside the airport zone, recently built and newly opened, are two full banking services:

Royal Bank in the compound with La Cantina restaurant; both a drive thru ATM and walk up ATM.

The Republic Bank is obliquely opposite with internal ATM service. 

A little distance away at the intersection leading to Pigeon Point, the Scotia Bank has a walk up ATM.  

Further down the Milford Road in the vicinity of Penny Savers supermarket there is a full First Citizens Bank with walk in ATM.  

And at Penny Savers supermarket itself near the entrance door there is a Republic Bank ATM machine.

Note that not all ATMs can accept all types of cards so you may have to try more than one before yours is accepted. Use normal precautions!