ok, I don't want to sound like I am advertising, but if you find that nothing you already owe is working on the plane, I am pretty sure they have a good kit in the duty free bar on board, you can even check online before you fly just to be sure. It is certainly cheaper than in any high-street shops.
Otherwise why not ask somebody in the terminal while you wait for your flight, I am sure they have everything you need in one of the many computer shops in terminal 4 - airside.
Happy flying!!!!
FBW
