One of the many great things about London is that if you are at a loose end you need only consult with the Oracle (the internet) and you can easily enough find a thing to do. So I bought a ticket for a tenner to see Swan Lake at the Royal Opera House. I had seen Swan Lake before but not at ROH.
I would really strongly recommend it for anyone who a) hasn’t been to the ballet before b) likes Tchaikovsky or c) likes ballet. I’ve been to a bunch of ballets this year (Romeo and Juliet and La Sylphide being my favourites) and I think there is a common misconception that ballet/opera is expensive or hard to get into. Personally I prefer ballet to opera, though I’d argue neither are inaccessible or necessarily expensive. There are tickets as cheap as £6 at the ROH, and many in the £10-20 range. These seats have ‘restricted view’ but after road testing various seats (and through general common sense) you can tell on the diagram which seats are not quite so restricted. I tend to pick seats on the upper slips, amphitheater left/right. You are fairly high up but it’s not ridiculous, and you aren’t terribly far from the stage either.
If you’ve never been to the ballet before Swan Lake is probably a good starting point, too. The plot is easy to follow and if you can’t hum the tunes already, you’ll recognise Tchaikovsky’s pieces when you hear them.