"Lists events in your area" is always the hard part.

The bars in my city don't have public APIs. If you start small and local, you could maybe get buy in from some places, "Send this address an email with event details and I will help you get butts in the door!"

Also if you build any app that lets you meet new people, especially new people with compatible interests, Match Group will buy you out and turn whatever you built into another tinder.

There is a number of centralised places for finding music events in London. None of them allow you to find people to go with. Regarding being bought out by Match: I wouldn't complain.