FlyerTalk Evangelist and Ambassador: The British Airways Club
Join Date: Jun 2008
Location: Somewhere between 0 and 13,000 metres high
Programs: AF/KL Life Plat, BA GGL+GfL, ALL Diam, Hilton Diam, Marriott Gold, blablablah, etc
Posts: 33,194
As long as it's straight return just search in Y and it will offer you both Y and C on both so you can choose one way Y and the return C. Bascially you can vary one thing (either class or destination) but what you cannot do is vary both at the same time using the website (you then need to call).