Bought the Apple World Travel Adapter Kit  before my flight to London in iStudio located in Changi Airport Terminal 3 for S$54.21. Since I was departing to London and have a valid boarding pass, I do not need to pay the 7% GST/tax, if not the normal price is S$58.
The Kit is designed to work with iPod, iPhone, iPad, Apple MagSafe Power Adapters (for MacBook and MacBook Pro), Portable Power Adapters (for iBook and PowerBook), and AirPort Express.
The AC plugs included in the World Travel Adapter Kit directly support outlets in North America, Japan, China, United Kingdom, Continental Europe, Korea, Australia, and Hong Kong.
Korea (Round Thick Pins)
Continental Europe (Round Thin Pins)
China (Flat Parallel Blades Without Holes)
North America, Japan (Flat Parallel Blades With Holes)
Australia, New Zealand (Flat Angled Blades)
UK, Hong Kong, Singapore (Three-Prong Blades)