SQL Relay 2014 resumes in the UK next week. SQL Relay is a series of 1 day events that are run throughout the UK.
Each event is a single track (or more in the case of London) conference, with between 50 and 200 attendees and 6-8 hour long talks by SQL Server professionals, MVPs, authors, technical experts etc. Thanks to the sponsors, this event is free to attend. Links and further info are available below. There is a waiting list for London.
Cardinal Place 80-100 Victoria Street London SW1E 5JL
Obviously the Underground or National Rail are the best ways to get to the office. Currently the roads in this part of London are still being dug up from over 2 years ago for CrossRail. It's truly horrific trying to navigate this area at the moment. So the walking route from the station to the office shown below is probably not going to be the one you take.
As far as local landmarks go, Westminster Cathedral is not far away from the Microsoft Offices.
I've been a few times (to the offices, not the cathedral!) and they are fantastic. There's even a very old Microsoft Surface table in one of the rooms.