Ok, to access the spark plugs, you will need to remove the engine covers, the coil covers, and the coils as they are located directly underneath the coils
unbolting and removing coils:
Once coils are off, use spark plug socket with extension and ratchet to remove plugs.
In case you need to know which cylinder is which:
The best service and repair manuals are actually online manuals- either AllData or Mitchell on Demand. They run $19.95 per year for a subscription.
I have checked the normal repair manual publications-Haynes, Chilton and Bentleys and cannot find one.
Your other option is thru Jaguar dealership