The best way I've found to remove paper from plasterboard is wallwik.

You can now get it in the UK from
http://www.wallwik-uk.com/products/w...al-sheets.html
(You only need the sheets, you can use your own sprayer to soak them).

Here are the photos from when I used it :-

http://homepage.ntlworld.com/chris.howard99/wallwik/