If you want a cheap flight from Southampton to Beijing, you've got zero airlines to choose from.
Make sure you use the search options above to search for flights to other airports in Beijing, not just Beijing Capital Int. Airport. The more options you look at, the better your chance of finding a cheap deal.
During this peak season, accommodation prices often increase too, so it's best to book early. Or you could keep your fingers crossed and hold out for a last-minute deal.