What's cheapest way to get tickets for the West End shows- Billy Elliott, Lion King, etc.??

[plocket]

Hi, Want to take ds to see some of these big shows, but ticket prices look so expensive. Is there a secret, way of getting them reasonable prices?? Any tips please let me know. And recommendations of shows. XX

August is Kidsweek in the West End - a child goes free with every paying adult. Might be booked up now but you could give it a try here: Kidsweek

Lastminute.com?