One of the great innovations that has happened in transport in the UK over recent years is that there has been a surge in airlines carrying people between different destinations within the country, where historically it would have only been international flights that would have operated from the UK commercially. For visitors as well as for residents, this makes it much easier to get around and to see different parts of the country quickly and conveniently.
Finding the routes is probably the big thing when it comes to booking and arranging domestic flights before a visit to the UK, but using the various sources online to find out this information will usually make it possible to find routes between the different airports and cities in the UK. It is important to bear in mind that the airports may be a short distance from the destination city, and it may require a bus or taxi journey to actually get into the heart of the city, and should be factored into the costs and time of such a journey.
When it comes to actually flying domestically in the UK, for residents it is quite straightforward, and would just require a form of identification such as a driving license, but for those from abroad carrying a passport like any other flights would be necessary. The check in advice from the airline may be less than that required for international flights, but factoring in some time for this may also be necessary when it comes to actually planning the journey.
Although the UK will generally be considered quite a small country, there is no doubt that getting around can often be quite a lengthy process, with journeys by car or train often taking many hours to travel relatively short distances. This is why the popularity of domestic flights in the UK has increased significantly recently, and has replaced the long train or car journeys for many people. For those cities that are linked by a direct airline service, the day long journey can now be replaced with a quick flight which can go from city to city in only a few hours.