A fabulous, inexpensive lunch spot atop tombstones in the crypt of St. Martin-in-the-Fields church on Trafalgar Square
Do not buy point-to-point tickets. What you want is an Oyster Card (possibly with a Travelcard transit pass).
Everyone knows Brits drive on the left side of the road—except for on one road in London. Savoy Court—the driveway off the Strand up to the entrance to the Savoy Hotel—is the only right-drive road in the U.K.