For all journeys by air, the passenger is responsible for having the correct documents for travel. The best way to be sure of having the right documentation is to contact the Embassy or High Commission of the country of destination. This is particularly important for countries requiring visas in addition to passports, because these requirements can change. It is vital you check with the destination country if you are holding anything other than a full passport for your country of residence. For example, unless you are a full British citizen, you may find that there are additional entry requirements for some countries, even though you have a British passport.
Do not be confused by the fact that airlines tend routinely to ask to see passengers' passports at check-in. This will be to check that the passenger checking in is the one named on the ticket (usually for security reasons), or to protect the airline against being fined for carrying a passenger to a country without the passenger having the correct documents for entry. These checks are not to protect the passenger from the consequences of having incomplete documentation.
If you are refused boarding because your papers are not in order, you will have no recourse to the airline; if you were travelling on a non-refundable ticket you will not be entitled to get your money back. If you are accepted by the airline for travel, but nevertheless get refused entry at the country of destination, you cannot later blame the airline. Indeed, under the conditions of your travel, the airline could seek reimbursement from you for any costs it incurred as a result of your failure to have the right documents.
Unfortunately, airline check-in agents do sometimes make mistakes (after all, they are not immigration experts trained in the entry requirements of every country served by their airline). In our experience, most problems are quickly sorted out at the time, and the passenger is put on a later flight, if necessary. However, occasionally the passenger is not able to travel, and the mistake has to be taken up with the airline customer relations department in the same way as any other complaint.
Some airlines, particularly no-frills airlines, require passengers to provide photographic identification in order to travel within the UK. Unfortunately, they do not all accept the same forms of photo ID. They will all accept a passport, and some airlines will accept identity cards such as a valid driving licence with photo, a Government-issued smart card, an armed forces identity card or a citizen's ID card.
Check with the airline or look at its website to see which type of photo ID it accepts. If you turn up at the airport with the wrong type of ID, you will be turned away at check-in. And you may be treated as a "no-show" and lose your money.
Many countries now require airlines to provide additional information about passengers, such as passport information, before they arrive in the country. Airlines prefer that you provide them with this information before going to the airport, in order to prevent delays at check-in. It is in everybody's interest to cooperate in doing so.