From MSE:


What if my flight or hotel is cancelled?

If your flight or accommodation is cancelled due to the coronavirus outbreak, even if there's an FCO warning in place for the country you're going to at the time that you go, the airline or hotel is likely to fully refund you for the booking you've made.

Under EU flight delay rules (which still apply this year despite Brexit, and which cover all flights leaving the UK or EU as well as flights to the UK/EU on a UK/EU airline), you're entitled to choose between:

EITHER a refund for the flight that was cancelled.
OR an alternative flight (airlines call this re-routing) to your destination.
We've seen that many airlines appear to be offering customers credit vouchers instead of refunds. You don't have to accept this, and if the airline were to go bust, you may not get your money back.