Id get a budget flight to Germany & train it to Moscow & then onto Beijing & train around a bit & fly back. You can go from calais to singapore all over land.
Trans Siberian Express is on my list
Probably gonna be a few years till I try this, but I want to travel around the world without using a plane once.
Trans Siberian to Beijing, then ship it down to Oz, across the Pacific to South America, drive up to east cost America then ship it to Africa. Then back up to London.
All Im missing is the bundle of money required to finance it