Assuming the plumbing system is similar to my 1998 car , there should be coolant in the expansion tank on the bulkhead. There is a marker in the tank which is visible if you shine a torch. The fluid should just cover this marker.
If there is nothing in the expansion tank I would assume that the rest of the system is not full and therefore you will need to do a bit of delving into the radiator , hoses , thermostat housing , and engine block drains, in order to ensure that :-
1 You don't have any tiny leaks
2 you don't have an air lock in the system somewhere.
Does the engine come up to temperature OK? It might be worth checking the operation of the thermostat if not (be warned access is not the easiest on injection cars)
Perhaps the best place to start would be to first fill the expansion tank to the level marker and then remove the radiator cap , and run the engine for a while until it reaches "normal" operating temperature. Keep topping it up so that the coolant is clearly visible in the radiator. Unless an air lock is present in the block this should bleed any air out. The level in the expansion tank might vary a bit, but that is usual.
Now that the air is (hopefully) out of the system put the radiator cap back on, and try again . This time the level in the expansion tank should remain at a very similar level AFTER the system has cooled down
The recommended fluid for the Rover V8 was always Bluecol which should be changed on a 2 or 3 year basis It is a concentrate which is diluted with (preferably distilled or dionised) water according to the amount of frost protection desired.
This is one place to purchase it :-
https://www.mymotorworld.com/blueco...I6AC8C2Za7MW-KGLfBJ72_idyJRoCoqUQAvD_BwEHowever more modern formulations are probably now perfectly acceptable
