The autosomal DNA test will give you two things:
1. Ethnicity, which can vary widely even between siblings. This is no help for genealogy. People moved around too much and that "English" mother could test out to be mostly Scandinavian and very little English due to Viking settlements in parts of England. Also Swiss will not break out separately. It would be lumped in with Western Europe.
2. A match list of people who share significant portions of DNA (relatives). By examining the closer matches and eliminating the ones that are on maternal siblings side, you can develop a list of people who could be related to you on your biological father's side.
For autosomal, I recommend Ancestry due to the size of its database and the fact that you can download the raw DNA for use at Family Tree DNA and GEDMATCH. If you test at FTDNA, you cannot upload to Ancestry.
As a male, you have an additional option to use in checking your father. That is the Y-DNA test. That is not offered by Ancestry so you will need to do that one at FTDNA. This tracks the straight father/son descent back into time. Anyone who comes up a match shares a common male ancestor in a straight male line only descent. I.e, your father, his father, his paternal grandfather etc and their male line only descendents.
The number and quality of matches you have will depend on how many people have tested.