Kev (I think that's your name, sorry if it's not),
Burkina Faso - wow, great opportunity to experience something out of the ordinary.
Burkina is generally considered one of the safest places in West Africa (although West Africa is generally pretty dangerous) - with a couple of exceptions.
The north of the country is really dangerous. The British FCO recommends you do not travel north of the town of Boulsa. The US state department says something similar, the Australian government has an official DO NOT TRAVEL warning for regions bordering Mali and Niger. The reason is because of the likelihood you'll be kidnapped. Two French nationals kidnapped in the region were found dead near the mali border in january this year.
If your work keeps you in and around the fabulously named capital - Ougadougou - then pickpocketing and bag snatching is about the worst of it. Although they've taken bag snatching to new heights! Experienced travellers recommend not carrying any bag AT ALL in the capital, or it'll get taken. The thieves love crowds (where it's difficult to chase them). The US says the crime hot spots are the U.N. Circle, Avenue Kwame N’Krumah, and the Central Market.
Another word of warning - if you're going to Burkina to WORK your WorldNomads policy doesn't cover you. Speak to the company who'll be employing you about appropriate insurance. If you work a little, then take PERSONAL time off to travel around Burkina) then you'll be okay with a WorldNomads policy, but check your policy and the level of cover.
Final word... there's no British consular service in Burkina (which makes it difficult if you need assistance), the nearest one is in Ghana. about 7 years ago