which plasterboard for ceiling

you certainly dont need a vapour barrier for downstairs. Paint is usually the only vapour barrier for upstairs.

I trust youre getting small boards for this, not 8x4s.

NT

Foil backed gives better vapour barrier. 12.5 mm boards are hard work fitting to a ceiling if your working alone. Double boarding with 9mm might be easier but then thats more expense.

With small boards, you can stitch three or four clouts in the stud where it's going and rest one edge on that It hold it in the exact place and gives you time to fiddle with wiring and to position your first two or three screws.

Standing on a beer crate or hop-up you can rest the other end of the sheet on your head. Once you put the other sheet to it you can tap the nails home.

With a large sheet, use a batton instead of the nail heads. And make a dead-man's rake (a tee piece made of a 3 or 4 foot length of batton nailed to a 2 x 2, long enough to reach from the floor and a little bit longer in order to give it some spring) to take the weight of the other end.

It need practice to get it right. You will then have both hands free to fix the sheet.