Last year I used China Eastern, flew to Shanghai, long layover, I think 8 hours, then to London Gatwick. Cheap but long and tiring.
This year I have booked with Qatar Airways, I was a Silver card member with them.
To BKK, then 6 hours to Doha, then 6 hours to LGW. 63, 779 THB return for 2 people.
Their service is the best in my opinion, friendly, good food, plenty booze, decent Airport lounges and shopping.
They use to fly from CM a few days a week, but discontinued since Covid.
If you avoid flying on certain days, eg weekends, you should get cheaper tickets.