I've used cake flour. pretty common in the states, though it's often common for a cake to be made with all purpose flour.
won't help you now, and might not help anyone ever, but there's a place in FoTan that has a decent collection of cake baking supplies - when you get out of the MTR station, instead of going toward the palazzo and the Marketplace, etc., go down the escalator, keep going down the street the escalator puts you on, and it's a little shop on the right.