If you’re delayed for over three hours, you’re entitled to financial compensation, which will be paid in euros. What you’ll get will depend on the distance of the flight, the length of the delay and if you’re flying to an EU country. You could be entitled to up to €600 (approx. £520) per passenger, except if the passenger travelled for free.
If your flight is delayed for over five hours, the airline must give you a refund if you decide not to take the flight. This includes onward flights and return flights, if they're part of the same journey.
If you’re delayed overnight, you’re entitled to accommodation, even if you decide not to take the flight. Airlines will reimburse you for ‘reasonable’ expenses, such as getting a taxi to the hotel.