What happens if I do not book all my tickets together – what are my passenger rights in such cases?
If you don't buy all your flights in the same booking, you are not covered by the airline's bond to secure that you reach your final destination in case of delays.
Example: If you buy a ticket to London in one booking and a second ticket from London to your onward destination in another booking and your first flight to London is delayed and you miss your connecting flight, you will most likely lose the ticket and have to buy a new one from London. In this case, you would not only lose the onward ticket from London, but also the return ticket to London.
You should also be aware that you can check your luggage all the way through or get boarding passes for all flights if you have separate tickets. You have to pick up your luggage at your transit point, go through customs, and check in once again. All in all, a very time-consuming process.