Sockets in Guinea-Bissau: Types C and F, supplied with 230 V at 50 Hz. No surprises on voltage: Guinea-Bissau runs at 230 V, the same range as at home in the UK.
You will find identical sockets in Egypt, Angola, Guinea and Cabo Verde. Watch out when moving on: Zimbabwe, Uganda and the Gambia use a completely different system. Across Africa this setup is fairly rare: 7 of 55 countries.
Protective earth
Grounded and ungrounded sockets may occur
Earthed sockets (Type F) and unearthed ones (Type C) exist side by side. For metal-bodied appliances the protective-earth path is what matters.