The Glow plug coming on, and the car going into limp home mode, is a default safety feature that occurs when the engine management system picks up any kind error message from the many sensors now used on the car.
I've found the glow plug light problem with my Jag, it was the air filter. Apparently Jaguar servicing change it every 3rd service (not a good idea). I changed mine, it is a new car. I had the EPR valve cleaned and a major diagnostic carried out by a local garage (who had the Jag diagnostic software). It turns out I also need a new Turbo; the actuator is sticking (£759.00 plus 3 hours labour). But hey, the main limp home mode problem is fixed and I can drive my Jag confident it will accelerate when press the gas.