When going along fine my landrover discovery suddenly revs like hell and pushes out big clouds of smoke what could be wrong?

what happens if you let it rev,and what does the white smoke smell like.

go to your land rover dealer seems your engine needs an overall

There are two main causes for this, especially given your limo's age:
- a leak, and you would notice little puddles of oil underneath the car
- worn piston rings - this will cause blue smoke from the exhaust, especially after idling for a few minutes
Have someone watch at the back, when the engine is hot, and after idling steadily for a few minutes, rev up suddenly to 2000-3000 RPM.
If you get a big cloud of blue smoke, the engine is worn.

The oil light is pressure not level. The noise at top of engine is most likely a valve tap. The oil isn't circulation through engine correctly. The problem could be a bad oil pump. Be careful driving the car you could cause major engine damage.

When was the last time that you change the engine oil? Sometimes it does that whe you have an excess of oil, check the level. But definitve white smoke means oil being burnt in the engine, you only see it in park because the smoke doesn't disperse like in motion.

a housing gasket is causing the antifreeze leak thats not a big problem to repair ,but the dash light are another issue and without the right connection cable and software programme to sort out the lights i would suggest the main dealer .

if it is a mems unit , it will need to be programed to the key fob and alarm . (there is no way round it).

check the terminal at the back of the alternator prone for loose connection sqeeze it together and refit it.

sounds like a blocked filter or low pump pressuer

need to replace the fuel regulater, located in engine bay.