Emirates will never fly direct flights to Bangkok from one London's airports, Norwegian will do that. The time difference looking at today's Emirates timetable seems to end up using 7 more hours traveling with Emirates compared with Nowegian (the shortest transfer times at DXB is 3:10 eastbound and 2:00 westbound).
The most probable Norwegian timetable for flights between LGW and BKK (local times):
Departure LGW 13:00
Arrival BKK 6:40 (next morning)
Duration 11:40
Departure BKK 09:00
Arrival LGW 16:00
Duration 13:00
Now let's look at what Emirates offer on their least time consuming combination:
Departure LGW 10:00
Arrival DXB 19:19:50
Departure DXB 23:00
Apprival BKK 08:20
Duration 16:20
Departure BKK 09:55
Arrival DXB 13:00
Departure DXB 15:00
Arrival LGW 19:30
Duration 15:35
The Norwegian (DU) timetable is based on the times and speeds used on timetables for OSL and ARN. You may wonder when you see arrival at 16:00 and departure at 13:00. Then I may continue with the send half of the timetable from LGW:
Departure LGW 17:30
Arrival JFK 20:00
Duration 7:30
Departure JFK 21:30
Arrival LGW 09:25
Duration 06:55
If Norwegian select to assign two B788 to cover BKK-LGW-JFK-LGW-BKK there will be daily flights to both BKK and JFK. At BKK and JFK the B788 will overlap with other company aircraft and an exchange of aircraft will be possible so that it can be flown to ARN for scheduled maintenance. The third B788 that is assigned for the FLL flights have a weekly one day stop at ARN (for scheduled maintenance and/or for exchange of aircraft).