It is not difficult. I did mine, no problems.
You are stupid if you don't replace the water pump while you are at it. They do fail (usually the impeller falls off inside and you get no water flow).
Basically take off battery connection, Driver side wheel, wheel arch plastic, under tray, radiator expansion bottle and ECU. Release belt and take off crank shaft pulley (4 torx bolts, not the big centre bolt). Take off plastic belt covers. Turn engine to TDC. slacken but dont remove cam pulley bolt (if replacing water pump) I used a big screwdriver through the spokes and resting on a small rige in the head to stop it tuning while I loosensed the bolt.
Slacken tensioner. Remove belt and transfer marks to new belt. Replace tensioners and remove cam puley if changing water pump. Reassemble, not forgetting to correctly set the cam belt tensioner ( push the small pin with a screwdriver while an asistant tightens the bolt in the center of the tensioner).
Note the diesel pump timing does not matter, but you must get the cam shaft and crank shaft positions exactly right on the new belt.
