From the Microsoft press release:
Interactive zones, surrounded by immersive video walls running throughout the store, will make this the best place to get hands-on with Surface, Windows, Office, Xbox and PC gaming, HoloLens mixed-reality and more. Designed to build connections with the local community, customers and businesses, our flagship Microsoft Store in London represents a unique way to deliver on our mission to empower every person and organisation on the planet to achieve more.
As with the well known Apple stores (and 'Genius bars'), the flagship Microsoft Store will feature "an Answer Desk, offering a dedicated area for customers to get tech support, trainings, repairs and advice from trusted advisors on Microsoft products and services. No matter where the device was purchased, the brand or operating system." Which raises the question that you probably could take a Lumia up for help and service after all.
Please, someone, try this in July! In fact, I think this might call for a rare AAWP field trip to the city!
Training is apparently part of the Store's remit too: "A Community Theatre, a space for tech, coding and STEM learning, will run free, year-round workshops and programmes for customers. So if you are a business owner looking for the latest tech to grow your business, a gamer who wants to join a community or show your skills in a tournament, a student wanting to brush up on coding or a teacher looking to bring Minecraft alive in the classroom, customers of all ages and abilities will be able to learn and develop their digital skills."
The flagship Microsoft Store in London joins Microsoft Store locations including flagships in New York and Sydney and some other stores across the US, Canada and Puerto Rico.