An Immigrant Visa is required by anyone seeking to take up indefinite or permanent residence in the U.S.
The Consulate General in Belfast does not issue immigrant visas. The Embassy in London is responsible for issuing immigrant visas to residents of the whole of the UK, including Northern Ireland.
For information about how to qualify for immigration including information about the Diversity Visa Program which is also known as the Visa Lottery, refer to Embassy London's Immigrant Visa page.
Note: No provision exists under U.S. visa law to qualify for immigration to the United States on the basis of retirement.