China forum

In order to travel in Tibet you legally must be part of an organized tour group - they will handle getting you the permits you need. You can arrange this through a limited number of companies in Napal, or otherwise there are many companies that offer tours in China and you can arrange everything with them over the internet before you travel. Travel only re-opened to foreigners in 2012, and there is no certainty that it may not suddenly be closed again at any time.

Another option is to go to Tibetan regions in provinces like Yunnan and Sichuan, which do not require special permits beyond your Chinese tourist vias. Western Sichuan has been difficult to access in since 2009, however, the area around Shangrila (Zhong Dian) in Yunnan is always open to travel and the Tibetans there are happier with the regional government which seems less repressive than in other parts of China - for example pictures of the DL were openly displayed in some temples. This option would also allow you to visit other areas in China like Tiger Leaping Gorge, Lijiang old town and Dali - a very popular circuit for backpackers. Probably not what you're looking for - but just a heads up.