Airlines must by law always display prices that include all the compulsory taxes, fees and charges, so you will always know the price of your flight.  Airlines should also clearly display any extra costs on their websites at the start of the booking process, so that you can see which of the optional charges you want to opt-in to.

Check the current airline fees and charges

Some airlines charge for carrying hold baggage, sports equipment and musical instruments. Some airlines charge for priority boarding, choosing a seat, and for using a credit card or debit card to purchase tickets. Others include most of these charges within the price of the ticket.

The CAA publishes an airline charges comparison table so that passengers can check the fees associated with different airfares.  This includes information on the cost of taking hold luggage on board, in-flight meals and reserving specific seats.

Source and text: website of the UK Civil Aviation Authority www.caa.co.uk