Is this what you are looking for?
SELECT LEFT(CONCAT(Product.Product_Code,SPACE(8)),8),
LEFT(CONCAT(Product.Description_Sales,SPACE(12)),12),
LEFT(CONCAT(Product.Description_Purchase,SPACE(30)),30)
FROM Product where Product.Description_Sales LIKE CONCAT(@status,'%')
This assumes that the column lengths should be 8, 12, and 30 respectively. You will need to alter the 8, 12, 30 numbers to your needs.
An Alternative:
SELECT CONCAT(LEFT(CONCAT(Product.Product_Code,SPACE(8)),8),
LEFT(CONCAT(Product.Description_Sales,SPACE(12)),12),
LEFT(CONCAT(Product.Description_Purchase,SPACE(30)),30))
FROM Product where Product.Description_Sales LIKE CONCAT(@status,'%')