Ask HN: Where do hackers meet in London?

There's Indie London, which is for indie hacking: https://www.meetup.com/indie-london/

There is dc4420 which is this evening near Euston and the last Tuesday of the month. They have talks and the people who attend are mostly corporate IT and infosec company people.

First friday of the month is London 2600, which is a bunch of geeks drinking and talking in the Angel pub.

I think thursday is electronic projects evening at South London Makerspace close to Herne Hill station.

There is an OWASP thing for website security and pubstandards which is webdevs and geeks drinking in a pub.

There is also Hack::Soho

Did you try London Hackspace?

Or have a look at hackspace.org.uk for some more options. Even if you do not want to join one of these, you might find people to direct you in the right direction. Most hack(er)spaces have open evening on Tuesdays.