Seen below, we found seats departing New York JFK on Friday, September 14, returning from London LGW on Tuesday, September 18.
Other dates are available for fall travel and sligthly higher fares can be found from December into January 2019 or for travel a little sooner in late February/early March 2018.
This is in Norwegian's LowFare ticket class, meaning that carry-ons weighing more than 22lbs will cost extra, as will any checked baggage. Seats in the LowFare+ ticket class for these dates are $555 round-trip. Heavier packers may consider just booking the mid-$500s round-trip fare to London Heathrow (LHR) on major carriers, British Airways, American, Virgin Atlantic, or Delta, and avoid any potential headaches with baggage weight.
Looking for a hotel in London? Here's what's available for the above dates on Hotelwatchdog.