Hello @LankyCape030052,
Welcome to Microsoft Flight Simulator! As the other posters have mentioned above, you’ll need to download World Update III: UK & Ireland from the in-sim Marketplace to add the enhanced scenery for London. This is a free download available to all players at no cost. There are also 13 other free World Updates for various other regions to download too! Feel free to get them all or just the ones that interest you.
Thanks,
MSFS Team