Applications for UK ancestral visa’s can only be made in the country where you normally reside. You cannot travel to the UK and make your application there.
As the UK ancestral visa is based on family ties there is not points testing as per other visa’s such as the Highly Skilled immigrant programme or Tier 1 and Tier 2 UK visa.
Successful applicants under the ancestral visa can set up their own business. Unlike the business visa there is no need to commit a certain amount of investment or create a certain amount of jobs.