Had to replace the battery in my 09 plate XF S. It was the original battery that was in it so nothing to complain about there but with that the holding bracket bolt snapped (the long bolt that goes into the floor of the boot)I have been told that I can get the remainder of the bolt out from underneath the car (with liberal use of release spray) but can't see where it protrudes from below. Does anyone know if it is hidden by anything, heatchield etc ?

 

It's not hidden by anything and it should be in plain sight and sticking down about 15 mm.
It might be covered in road grime and/or sealant of some type, just have a good poke around under there and you should be able to find it.