Tap on the wall you will here a difference it it sounds solid it's a stud if it sounds hollow then it's a gap also if it is a new wall the studs will be 600mm center's hope this helps !!
I've just ordered a stud detector. My tube of pollyfilla was dried up so now I have to stare at this mess for the next two weeks I've tapped the whole wall and there's nothing behind it as far as I can tell. I wanted to mount a 3rd PC monitor above my others so I can watch TV while working. I guess thats not going to happen.