Not long moved into a 2 bed flat and apart from the bathroom and toilet the whole place needs to be redecorated. I've stripped most of the wallpaper already and the backing came off easily. Before i paint do i need to use an undercoat or can i just pick a colour and start painting? Also i have parts of the walls that are bare plaster (where an old fireplace was ripped out) do i need to seal/ use an undercoat or can i paint straight onto it? Also what sort of paints do you advise i use i have no idea what the difference between silk/matt etc are! and last question how do i remove the old wallpaper from behind a radiator without removing the thing as i don't wanna do that if i can avoid it.