I have attempted to travel from Singapore to London overland, and in the end abort the trip when I reached Astana, Kazakhstan. My itinerary is as follows:
- Kuala Lumpur - via bus transfer from Aeroline
- Butterworth - via train from KL
- Hatyai - via cab and car transfer from Butterworth
- Bangkok - via train from Hatyai
- Aranyaprathet and Poipet (border town of Bangkok-Cambodia) - via car
- Siem Reap - via car transfer from Poipet
- Phnom Penh - via car transfer from Siem Reap
- Ho Chi Minh City - via bus
- Hanoi - via train
- Nanning - via train
- Beijing - via train
- Xi'an - via train
- Urumqi - via train
- Almaty - via train
- Astana - via train
From Astana, you can book a train to Moscow, Saint Petersburg, and went on further to Europe.
From Singapore onwards, I would say set aside about USD5,000 to USD6,000 to be safe, depending on your preferences. I have land myself in several scams as I have no choice but to make the payment. Guess that's part and parcel of learning while travelling. Also, long-distance travel on train can be rather tiring and exhausting. So you might not even want to choose the cheapest alternative all the time. One issue with China trains is that if you are rushing, it is difficult for you to book the tickets that you want as well.
I set aside two months to complete the whole journey. In the end, we took slightly more than one month to reach Astana. My take is two months might be a little too rush, given that you might not always go according to your plan. During this trip, I have cancelled several destinations due to inability to find the transport, and end up staying in one city longer than expected. Still, I think this is the beauty of a long distance trip like this.