The hardest part of doing the headlining is actually recovering it. Taking it out in one piece is simplicity itself. Remove the grab handles and sunvisors, prise the a,b and c pillar trims away (Don't be scared to do this, they're just a push fit to the car), also remove the light unit and finishing trim around the sunroof if you have one and pull it out of the car, It's that simple!
I tried to recover mine yesterday but made a right mess of it as I used material that was just to thick and it just wasn't malleable enough!