4 weeks? I don't think you can travel around with them everyday..... If they dunno English, I guess you will need some Chinese DVDs or even a TVB satellite channel to entertain them
By the way, some nice museums in London are free of charge. Or, you can make a short trip to Europe. Try to have a look at the websites like www.eurostar.com or www.lastminute.com
ALL ANIMALS ARE EQUAL, BUT SOME ANIMALS ARE MORE EQUAL THAN OTHERS.