Do you mind to share how much your tickets cost and which airline will you take? ...
The airline I booked was BA. The costs (including taxes) are about $10500 (per adult) and about $8500 (per child).
The only available time for my children are summary holiday which is a high season for air tickets. I only guess there will be no discount offer for flight ticket during high season.
I checked the CX ticket cost, it is almost $10000 for low season.
As you have booked tickets from BA, I'd like to remind you that BA is a quite strict airline. The weight of your suitcase should be below 24kg, even though it is just 24.1kg, the ground staff will request you to open your suitcase and re-arrange your belongings.
As BA is a British company, the entertainment provided on the flight mostly is in English. Your kids may feel a bit bored if they are not used to listen to English.
Sorry , BA won\'t combine the total weight! You have to equally distribute your stuffs. But luckily, it is a summer time , clothes are lighter and thinner.
Relatively few and out-dated Chinese or Cantonese films when comparing with CX
for kids, I highly recommend natural history museum, if have time remained, go next door science museum. search for musical that's suitable for your kids ,tickets sold out quickly. British museum is rather big, pick several spots to visit. my kids love London since I brought them there last summer.