We want to make sure that as many fans as possible get the chance to book. When you select your seats, you're actually holding those tickets while you go through the checkout process, so no one else can access them.
We have to limit the amount of time you can hold the tickets, otherwise, we'd be left in a position where someone can grab the tickets, go and make a cup of tea, pop off down to the shop etc., then decide that, actually, they don't want them. This wouldn't be very fair to all the other fans who desperately want tickets and are ready to pay there and then but can't get their hands on any.
The amount of time you have can vary depending on how busy the website is, but we'll always make sure there's enough time to fill in your details and check the information carefully before paying for your tickets.