I have a 2007 XJ8,
When car is sitting there is no give in the rear shocks,
the front are fine when you push down car gives and bounces back.
But when you push down on the back of the car there is ZERO give??
Is the front too soft or the rear to stiff??

 

Generally the whole suspension is fairly rigid when the car is at rest. When the car is stationary with the ignition off all four dampers go to their unenergised state which is the 'hard' setting. So, what is odd is not that you say the rear is hard but that the front is soft.

Do you know that you have standard Jag air suspension units on the front, or have they had some form of coil spring conversion fitted ? Most conversions seem to have single setting dampers; some of those have electrical connections to fool the suspension module into thinking it has switchable dampers when it hasn't (otherwise it will continually report a damper fault).