If a UK based union wants to hold a strike, they must give 7 days’ notice for the strike dates. This can only happen after a ballot has taken place, and the notice must be served within 28 days of the result of the ballot being published.
In occasions such as this, the airline will probably cancel short haul flights and concentrate on the long haul flights. As the short haul flights are generally more frequent, it’s easier to rebook passengers.
If you are concerned about your trip and you want to cancel your ticket so that you can book with another airline you may not receive a refund. Any refund percentage for your ticket would have been mentioned in the Fare Rules. However you may be able to rebook for a different date for free (despite the rules).
If the airline cancels your flight, then the EU Regulations come into play, which means that you should receive a full refund for any unused part of your ticket within 7 days or be placed on a replacement flight as close to the original departure time as possible.
You could be out of pocket
If you are at the airport, then the delay compensation will come into effect as mentioned above. If you have packaged your own trip, then in occasions such as these you may find that you could lose a lot of money.
If you had booked a packaged holiday then the tour operator would have had to make it possible for the trip to continue, even if this means booking you on to another flight the next day.
An airline which cannot fly does not have to refund you for any other items booked for your trip such as hotels and hire cars. If these companies will not refund you, you will have to try claiming on your travel insurance. But if the trip was booked after the ballot was announced then you may find that the insurers won’t pay out.
You could try seeking compensation form the airline through the courts but there is a strike clause in the EU Regulations.