In a recent post to the Symfony blog they've posted the official announcement of SymfonyLive London 2018:

We’re so thrilled and excited to announce SymfonyLive London! We’ve just confirmed the official dates, SymfonyLive London will be held on September 28th at the Park Plaza Westminster! Symfony is proud to organize the 7th edition of the British Symfony conference and to welcome the Symfony community from all over the UK and Europe.

Join us to share Symfony best practices, experience, knowledge, make new contacts, and hear the latest developments with the framework!

Come to attend SymfonyLive London, conference day will be on September 28th, and the pre-conference workshops will take place, one day before the conference, on September 27th.

Early Bird registration is already open and you can pick up main event tickets for 129£ and full conference tickets (includes training) for 543£. Additionally, if you'd like to speak at this year's event, the Call for Papers is still open and runs until June 17th.