iBook air/london power

What is the best way to get power both on the plane, and in London.
brandenb wrote on :

I'm getting ready to take a trip to London, and I would like to take my iBook G4 with me.

What is the best way to get power both on the plane, and in London. Should I get a 12v power supply for the plane (Boing 777-200), and then the foreign power adapters from Apple for the stock power supply? Or is there a single solution that will do both?

Thanks