Delta and Virgin Atlantic have round-trip flights from Dallas (DFW/DAL) to London (LHR) for $351-$380 with a connection. Flights in May, August, September, October, November, December, January, and February. Departures on Tuesday and Wednesday.
Note: New Years Eve is available if you can do a 10-day stay or longer.Note: Upgrades into Delta Comfort+ available for +$498.
Note: Carry-on bag is allowed for free on Delta and Virgin Atlantic. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.