hi
you have a few options, get a kit off ebay, remove yours, remove the cloth, rub all the foam off and stick new material on, about £100
or get a new one, new headliner off ebay, grp one, dont hold the damp like the hardboard one and just remove and fit the new one, about £250
or take it somewhere to get it done, around £500 to £600
cheers
Joe