Yes, you are correct.
Two Thai Airway flights per day from Heathrow, and one Eva Air flight per day from Heathrow.
Statistical data on the internet shows that in year 2022, just over 200,000 UK citizens visited Thailand.
So divide that figure by 365 days and your left with 547 UK passengers will travel to Thailand each day.
Eva air uses Airbus 330 aircraft which has over 400 seats .
So 3 times 400 equals 1200 seats.
That's more than enough plane seats.
Do you think British Airways will reintroduce flights to Thailand ?