Best way to go is to go out and get a power inverter. Then you dont' have to do any D&D. Just plug in the computer and periphals and your good to go.
A 300W inverter cost me around 40 bucks and i can plug the computer in and whatever periphals i need as well.
inverters are really simple technology. you should be able to get em at automotive stores or Walmart type stores have em too.
i think you should be able to find one for around 25-35 pounds.
don't bother with the ones advertised as laptop inverters or ones from computer stores. they are overpriced and underpowered. 300 Watts should be sufficient for any application
The inverter i have is pretty solid. It's by Portawatts (sic) and it's been going good for over a month now. My computer has a 100W power supply and is plugged into the inverter directly.
The only other devices that are plugged in are is the Sony PSOne LCD screen and the GPRS cel phone.
You can always put a surge protecter or UPS if ya really need to.