I need to organise a work summer party for 20 people. We're from all over the UK, but we want to focus on a fun day in London. We need a fun activity (not team building) that we can all do (ages vary) and then maybe a nice dinner somewhere (riverside would be nice). I've only been to London a handful of times, so I don't really know where to start. Apparently boat parties are a no go. All ideas will be much appreciated. Thank you.