Unlikely to be Stansted for a base due to a lack of slots especially early morning departures. Gatwick no doubt also suffers the same.
From TTG:
TUI UK’S no-frills airline Thomsonfly is now cheaper to run than any of its competitors, according to the operator.
Speaking in Orlando, Tui UK managing director Peter Rothwell claimed: “The cost of us putting people through the air is now cheaper than any of our low-cost rivals.” Tui is using the economics of its Britannia Airways charter fleet to launch a hybrid airline. It is rebranding all its Britannia fleet as Thomsonfly.
The rebrand will enable it to offer unbonded seats to compete with no-frills rivals. On the same flights, it will also carry passengers that have bought Atol-bonded packages or conventional seat-only tickets. Rothwell admitted that the dominance of easyJet and Ryanair at Luton and Stansted was an impediment to the company’s expansion plans, but stated: “I cannot afford not to be in Luton and Stansted".