The cheapest one-way flight from Shannon (SNN) (SNN) was to London (LHR) at €40. A simple way to find cheap flights with Expedia is to enter your preferred dates and destination, and then sort your results by price. These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply. One of the best methods to land a cheap flight is to be flexible with when you travel. Start by searching for flights on the dates you'd like, then click on "Flexible dates" above the results. You'll see the cheapest prices for nearby days. You can also refine your search and filter for specific airlines, departure and arrival times, included baggage and more.