Sometimes, we really should listen to friends. Like when they say, “Bring an umbrella because it always rains in London,” you MUST grab an umbrella even if the sun is bright and shining when you leave the apartment to explore. Because those Londoners are right – it always rains in their corner of the Earth. Another thing that’s always in London are tourists — all 17 million of them spending £11 billion like London wasn’t the sixth most expensive city in the world. Last year, London ranked the second most visited city, after Hong Kong.     At Heathrow alone, prepare to queue an hour or two for immigration clearance. It’s nothing like that famous opening scene in “Love Actually,” when Hugh Grant says in his perfect Love-me-I’m-British accent: “Whenever I get gloomy with the state of the world, I think about the arrivals gate at Heathrow Airport. General opinion’s starting to make out that we live in a world of hatred and greed, but I don’t see that… If you look for it, I’ve got …