May be this will help you.
SELECT SUBSTRING(myColumn, 1, CASE CHARINDEX('/', myColumn) WHEN 0 THEN LEN(myColumn) ELSE CHARINDEX('/', myColumn) - 1 END) AS FirstName ,SUBSTRING(myColumn, CASE CHARINDEX('/', myColumn) WHEN 0 THEN LEN(myColumn) + 1 ELSE CHARINDEX('/', myColumn) + 1 END, 1000) AS LastName FROM MyTable