Day out without kids, London

[CoonRapids]

I have a rare kids free day in London, meeting up with a friend around Charing X/Southbank on Saturday. But what should we do, if not just wander the South Bank and have lunch? Any recommendations for exhibitions etc. or other relaxing, kids free activities? Friend has said I should decide what we do (she has no kids), but I'm too tired out to think or research it, so am hoping someone will know!! Thanks

Somerset House fountains!! Take spare clothes! There are some at South Bank as well but these are more spectacular- fun display every hour. FREE!!!

Free is good, thanks! Yes, forgot about Somerset house. I used to live and work in London (used to pop into Somerset house for lunch ). Before I would have instinctively known where and what to do, but having moved out to the Thames Valley, not visited central London since 2008 and 3 kids later am brain dead and clueless!!

Hmmm, I think a busy bar or restaurant would be my choice.

Depends what you like. I would like a bit of culture with no interruptions eg Tate Modern or National Portrait Gallery followed by a very long leisurely lunch somewhere fabulous. I would avoid anywhere with children like the plague, I hate places with children about when I don't have mine with me, I am just miserable and miss mine.