When moving to another country, it is always good to learn the local language, not only as a matter of surviving but also because people will recognise and appreciate the effort. Especially in a country like Angola, where English is not widely spoken amongst the local population, unless you are near the border with Zambia and Namibia or in places with a high expat presence.
If you are going to a major city or you are going to work with skilled or highly educated people, your best bet is to learn Portuguese. If you are going somewhere more remote or with people that have not completed their education, you may want to attempt to learn the local language, or at least some Kimbundu or Umbundu, the most widely spoken Bantu languages of the country.
Since finding Bantu language lessons is not as easy as finding Portuguese lessons, the best way to learn is by practicing and asking people around you whether they know somebody that could teach you. Portuguese language schools are harder to find outside cities.
Nowadays is very easy to find beginner level lessons for local languages on YouTube. Also, watching local TV and listening to the radio is a way of learning without really trying too hard! Fortunately, many of the Bantu languages are similar and easy to learn.
One of the best places to learn Portuguese and Kimbundu is the Alliance Française in Luanda .
For the Kikongo language, you can look at Centro Cultural de Bakongo on Facebook where they publish the schedule of the lessons and the prices. They have lessons in Luanda and in Mbanza-Kongo.Or you can learn online through videos on the Malaki Afro TV website.