[retiredbaker]

Cake flour like Swans Down is like White Lily here in the deep south: both are higher in starch and lower in protein unlike typical AP flours such as Gold Medal, Pillsbury and King Arthur. If you've ever wanted to thicken a liquid such as roux or soup, you'd be much better off using a cake flour than AP because of the higher starch content in the former. Think corn starch for thickening apple pie (and cherry pie?) filling.

In practice it doesn't hold up, cake flour thickened sauces break down and become soupy if held at serving temps.
Tried it in a curry sauce and it broke down during dinner service, I threw some potato starch in for a quick rescue .

 

[retiredbaker]

Im trying to make an angel cake but unfortunately there is no cake flour down under... There in only plain flour and self-rising flour available. Some people have told me that self-rising is actually cake flour but have read differently over the internet. Would anyone know an acceptable subsitute or whether I can really use self-rising?

They're probably following EU food rules, its probably the bromated thing they don't like, you can get cancer if you stare at the bag too long. True story.

You should get similar result with pastry flour, the major difference is its not bleached so has a slight gray tint.

Maybe try lightly baking the self Raising flour to stunt the baking powder, BP becomes weak if stored at too high temperature.