Visa required for 2 night stopover in Beijing?

My wife is cabin crew on British Airways and is flying to Beijing, landing local time at 10h25 Friday 29th March, and departing local time at 12h10 31st March. My daugher and I were thinking of joining her on the trip. i.e. London Heathrow - Beijing - London Heathrow. We would like to have a quick tour, taking in the Great Wall of China and Forbidden City for example. Will we need visas? We are all on British passports.