is it normal to not be able to engage sport mode while driving?

 

Not normal

But - do you know that you have to press down on the gear selector dial before turning to S? To avoid accidental selection

 

oh wow. no i did not know that.
thanks for the lesson.
tomorrow i have a 150 mile drive home with the xf, a little nervous as it had 2 coolant leaks at the dealership, 1, a pipe nipple had snapped and 2, the thermostat housing had a leak.
the issues were fixed with jaguar parts so it should be fine.