If any of you see this before you go, stop off at a Halfords on the way:
CLICK MEGet maybe the 150W normal or e-can one, Ill bring my wee lappy (lots of music), and the FM transmitter thingy, sorted!
EDIT: Yeesh what a long URL, edited to fit page... Just search for inverter on the halfrauds site if it times out or anything. Would go get the goods myself from my local Maplin but they seem to charge a tenner extra! Over Halfords!
EDIT2: I would only use it when the lappy actually needed charging, and then only on the go - dont want to flatten our car battery!