http://www.jagrepair.com/JaguarXF.htm
If you have a look there Nick, there are several procedures, reprogramming the emergency brake (handbrake), auto-windows and so on and another section on the battery which should give the information you need.
I'm guessing the original battery was still in the car and you used jump leads from your L200? If so, i seriously doubt any car would start if the original battery was completely flat, even without the various procedures to reprogram everything. Also make sure whatever battery you fit in the XF is fully charged as a emi-charged battery can void the alternator warranty.
I'd wait until tuesday, fit the new battery then go through all the procedures. After that, hopefully you'll have a fully runnign car again, you may also have to go through a driving procedure to get the ECU to re-learn the fuel trims etc.