There are two three different types of 777-300ERs. The first has the Sky cruiser seats in F and the 'regular' J seats. This is used on EK003/007/029 and EK001 on Tue. The second has Sky cruiser seats in F and lie-flat J seats. This is used on EK001 daily ex Tue. The third has suites in F and lie-flat J seats. This is not used to LHR but to other cities like CDG, JFK and JNB.
Cheers,