If you have some more time to spare on your next London trip, you can visit Camden Market (undergroundstations Camden Lock or Mornington Crescent). It has a lot of international eatingstands, craftsmenshops and a really young vibe.
From there you can easily go to Primrose Hill, where you can have a fab view of London. Regent’s Park and London Zoo are all within hikingdistance.
To the Southeast you have Greenwich; the place where the GMT is situated. Funny to stand in other timezones & it is located on a hill, surrounded by a green park.
One of my favourites is Tate Modern: a rennovated building next to the Millenium Walk Bridge, that offers a nice view over the river Thames and St Paul’s Cathedral (and a lot of other well known buildings). There you can have a decent meal or just a drink. Each time I visit London, I’m checking in for the view and at night it’s even better to sit, eat and watch everything).
Hope you further enjoy exploring Europe & keep writing your experiences (they are fun to read).