foil backed plasterboard

I have recently pulled the plaster off one of a wall in my house because it was practicaly crumbling away. It is an exterior cavity wall. What I plan to do is to screw batens to the wall then screw the plasterboard to the baten. Beceause It is an exterior wall I would like to use foil backed plasterboard for insulation. I dont have any foil backed plasterboard but I do have plenty of ordinary plasterboard, would i be able to get the same effect if I bought a roll of thermal insulation foil to put between the plasterboard and batens? if so whats the best way to go about it? if not can someone direct me to a cheap place to get some foil backed plasterboard?

Thanks in advance

Foil backed board is not insulating.

Its a vapour barrier to stop moisture from the room getting into the wall

Ok, Maybe not insulation but it is an exterior wall, so I feel i still need the foil backing. I just want to know if I can do the same job with normal plasterboard and sereprate foil like this:

http://www.wickes.co.uk/FOIL-INSULA...vJOxcInvY1H4JwBcSZ2MIfCIMv2VNq1z WJ9bQPNXrg==

And if this would do the trick what would be the best way to do it? if not wheres the best place to get cheap foil backed plasterboard?

you could use a polythene sheeting over your battens and then fix the normal boards over the top ,it'll do the same job

foil backed boards ain't really the most expensive of items.

see sense, spend a penny and save a pound.