Just knock it out as best you can and fit a second hand light unit. The way the panel has creased the boot floor has moved down, judging by the rusty wheel arch the poor thing is not long for this world.
I would check them first before replacement, they look like very thin spark plugs poking out of the cylinder head. Disconnect the power bar and use a multimeter to check the resistance, should be very low almost a short circuit if there is infinite resistance then it is blown.
Now the pain starts! Check on YouTube for glow plug replacement videos when they snap off.
If its a courtesy car the Ford dealer can arrange insurance and should have handed you a hire agreement with the T&C's. Read that and see what you are liable for, there may be an excess to pay or you are fully covered.