Each year Ealing hosts a summer festival which includes sessions in one of ealings parks including jazz, comedy, world music, and more. For full details have a look at the weblink. Entry is cheap (some sessions just a few pounds), sessions are during the day and evening, you can take in your own food and booze for picnics. Also stalls and shops at each session. Relaxed atmosphere; great for kids as well as adults. Mainly outside but some sheltered stages.