TodayTix

If you use the todaytix app, you can search for shows across different theatres on specific dates to make a list of what you’re interested in. My favourite theatres are the National and the Old Vic, but really they’re all great.

I’d always double check the ticket price to the theatre directly, because sometimes they charge more, but a lot of times (especially the day before or day of) they drop the ticket prices to fill the seats.