the easiest and probably the cheapest way to get bluetooth in your car is just to replace the stereo with a modern one. There are fascia kits available which allow you to put either a single or double din unit in in place of the Jag unit.
Retro fitting the Jag touch screen is an awful lot of work and as the CAN Bus cables probably aren't fitted to your car would be pretty expensive. After all that faff you end up with a satnav unit that is already 4 years out of date and won't be getting any new map updates.
I have exactly the same setup as you except that I don't have the autochanger. I deliberately bought the car without the touch screen satnav because I knew I wanted to replace the stereo. I got a nice Sony unit fitted which gives me not only bluetooth but also DAB and the ability to play music from a USB stick. Cost me around £150 including the fascia kit and required cables including a DAB ariel.
