Ok I'm setting the record straight on this; buying online/through phone booking is sold out. However, wait til the show is open and if you go to the theatre box office in person on the morning of the show (Donmar opens at 10am, you will need to be there at least an hour before that and you can't actually buy the tickets until 10.30am) you want to see they will always have a number of day seats (Donmar releases a minimum of 10 tickets, only 2 per person) and standing tickets available. They take tend to only take credit/debit cards so beware & check the Donmar policy before you go. It's only the pre-booking that is sold out, and taking the risk & buying day or standing tickets tends to be much cheaper & you don't have to pay the extortionate booking fee either.