There is no British Embassy in Gabon. In an emergency, you can get consular assistance from the British Honorary Consul in Libreville. Otherwise, you should contact the British High Commission in Yaoundé, Cameroon. See Consular assistance.
There is a low threat from terrorism. See Terrorism.
There have been attacks of armed robbery on commercial shipping in the Gulf of Guinea. See Sea travel.
Take out comprehensive travel and medical insurance before you travel.