MySQL - reformat a column value dependant on existing value
In Mysql you can use CONCAT function to concatenate values ,you can use your logic in if() to show yes/no according to the criteria.if you want to show the value from column when its not empty then replace 'Yes' with your column name 

SELECT 
   `d`.`FirstName` AS `First Name`,
   `d`.`LastName` AS `Last Name`,
   `o`.`Name` AS `Organisation`,
    IF (`d`.`PhoneWork`  IS NOT NULL AND `d`.areacode IS NOT NULL,CONCAT(`d`.`PhoneWork`,' ',`d`.areacode),'your value') AS `concat_colum`,
    IF (`d`.`PhoneWork`  IS NOT NULL,'Yes','No') AS `WorkPhone`,
    IF (`d`.`areacode`  IS NOT NULL,'Yes','No') AS `areacode`,
   `d`.`EmailAddress` AS `Email Address`,
FROM `delegate` d
JOIN `organisation` o ON(`d`.`OrganisationID` = `o`.`ID`)


You can do the same by using CASE too

SELECT 
   `d`.`FirstName` AS `First Name`,
   `d`.`LastName` AS `Last Name`,
   `o`.`Name` AS `Organisation`,
    CASE WHEN 
    `d`.`PhoneWork`  IS NOT NULL AND `d`.areacode IS NOT NULL
    THEN CONCAT(`d`.`PhoneWork`,' ',`d`.areacode)
    ELSE 'your value' END  AS `concat_colum`,
    CASE WHEN `d`.`PhoneWork`  IS NOT NULL THEN 'Yes' ELSE 'No' END AS `WorkPhone`,
    CASE WHEN `d`.`areacode`  IS NOT NULL THEN 'Yes' ELSE 'No' END  AS `areacode`,    
   `d`.`EmailAddress` AS `Email Address`,
FROM `delegate` d
JOIN `organisation` o ON(`d`.`OrganisationID` = `o`.`ID`)