the clutch thing is not an immobiliser, its just a safety thing they do on US cars with manual gearboxes. it stops them starting the car in gear and it roaring off, due to them using auto boxes a lot more.
you do wait for the glow plug light to go out before starting it in the cold?
( its a little orange light that lights up when the ignition is switched on, its got a coil of wire symbol on it)
we are mostly just over in birmimgham so you are not a million miles away.
to safely tow the jeep , you should put it in neutral and also make sure the transfer box is in neutral as well.