Where to find really cheap theatre tickets? for the 5th march matinee? London?

Depends on whether you really want to see a musical or not, or whether you would be happy to see just a straight play? Time Out's website has a theatre section which I believe has listings and ratings for shows, so definitely worth a shot :) And look for shows that are close to ending, because they tend to have cheaper tickets :) Also, try not to book seats in the stalls, because they are so much more expensive that Dress Circle (which actually has better views of the stage). Hope this helps :) x