I did the headlining in my X350 a couple of years ago. The kit which consisted of material and glue cost about £80. I removed the polystyrene biscuit as its called and took it to an Upholsterer for him to fit the material (another £100 and something) A big but enjoyable job to remove and replace but I could see the glueing bit ending in tears so I left it to a professional. The recommended way is to remove the windscreen but it can be bent and removed through the back door opening. This was on an XJ X350 but I would think the Xtype would be similar. No problems since.
Good luck