If you like adventure then try hiring a four wheel drive car in Cameroon! After driving in the rainy season you'll feel up to entering any cross-country competition and you'll probably do really well. There are tarred roads in Yaounde and between large towns but these are often in poor condition. Street lighting is poor and non-existent outside of main areas. Pedestrians and stray animals are major hazards in town, and many vehicles are poorly lit and badly driven. Out of town expect dirt roads apart from the main road.
Don't drive at night out of towns, particularly on the Yaoundé-Douala trunk road, where accidents are common. Always lock the car doors when driving.
British driving licenses and International Driving Permits may be used on first arrival, but you should obtain a Cameroonian license as soon as possible after arrival. Holders of a British driving license can do this by filling in a form at the Delegation of Transport.