Booking your trip from Robin Hood Airport (DSA) to Heathrow Airport last minute could be your ticket to a fantastic deal. However, it might cost you a whole lot more! If you’d prefer not to take any chances, book well ahead of your departure date. In fact, Expedia has some of the biggest bargains as far ahead as 12 months in advance. If your preferred air carrier hasn’t released tickets yet, check back often as deals are updated on Expedia all the time.