This company specialises in holidays to Cape Verde. I find, having booked with them to Senegal and The Gambia that they are very reliable. You can download their brochure from
https://www.capeverde.co.uk/brochure
Page 54 states:-
CURRENCY
The local currency in Cape Verde is the Escudo, expressed as CV Esc or $ before the amount which can only be obtained on the islands. We recommend that you take Euros or Sterling.
MEDICATION
No vaccinations are required for Cape Verde, however for young children, the elderly or those with any pre-existing conditions please discuss with your GP. There is no malaria present in Cape Verde with the exception of the island of Santiago from September to November. If you are visiting Santiago during this time please also check with your GP for
the latest advice.
PASSPORTS AND VISAS
A full 10-year British passport is required for entry into Cape Verde. All British nationals require a visa to enter Cape Verde which is only issued at the point of entry.