Columbia is the state capital of South Carolina. It is a university town with a large proportion of its workers employed in the public sector. As such, it is relatively liberal when compared with the rest of South Carolina.
As one of America's older cities, it contains many walking neighbourhoods, of the type that will be familiar to Brits. However, it has only a skeleton bus service, so those who are used to a car-free lifestyle may wish to look elsewhere when choosing an American city to relocate to.
There follows a partial list of stores offering British groceries for sale:
Lil's Old English Shoppe, 599 Whaley Street
JM Emporium, 9221 Two Notch Road (Indian grocer with some British products)
World Market (2 locations), 210 Forum Drive and 6090 Garners Ferry Road.
There is a British Expats meetup once a month. See here for details.