I will be in London in late June.
The Academy of Saint-Martin-in-the-Fields is performing at The Anvil in Basingstoke one evening, and I'd love to go hear them.
South Western Railway has frequent direct trains (seems like as many as 6-8 per hour) between Waterloo Station and Basingstoke, and the trip is less than an hour, so I definitely think this is doable.
My question is, do I need to buy train tickets in advance, or can I show up at the train station and buy tickets for the next train. I'm especially thinking about returning to London after the concert. I can guess how long the concert will be, but it would be nice to have some flexibility.