I don't think you can utilise the 2nd European entry/exit with MRU. Would also need to be transit between other continent and one of the below African countries when utilising this exception.
ONLY ONE INTERCONTINENTAL DEPARTURE AND ONE INTERCONTINENTAL ARRIVAL PERMITTED IN EACH CONTINENT EXCEPT AS FOLLOWS - ...snip... TWO PERMITTED IN EUROPE WHEN ONE IS A TRANSFER WITHOUT STOPOVER BETWEEN GHANA/NIGERIA/KENYA/UGANDA/TANZANIA AND ANOTHER CONTINENT.
Would work if you move the DXB trip to the start of the itinerary, and end the itinerary with NRT-xLHR-<a city in aforementioned African countries>.