Your best bet for an overland trip at the moment may be to...
Travel from India, to Kathmandu in Nepal (look up seat 61.com -> Nepal, eg you could get train to Gorakhpur).
Get a bus from there to Lhasa (although there are conflicting reports about whether that is still running, or perhaps go on an organised tour).
From there you can catch a train on the relatively new Qinghai-Lhasa Railway to the rest of China, which features the highest section of railway, railway station & railway tunnel in the world.
Also note, there are no border crossings between India & Tibet that are open to foreigners, you have to go via Nepal instead. (Cannot post source due to limits on low-rep accounts)