Will 'backing paper' solve dodgy walls?

Lining paper will certainly help, but in limited situations. It won't unfortunately cover "stipple" especially if it's any way rough at all. It will however cover light blemishes and small cracks, but I'd advise you to fill and sand as much as possible before applying the paper. While it does come in different grades 800 to 1400. Which basically means how thick the lining paper is. You can also get embossed paper as well, which has a texture or design to it. It might be helpful if you could upload a picture, as this would give a better idea how best to approach the situation.