hi sebbie,
i did this trip last year. and i was catched by police after seven days in tibet. so take care!
i have some usefull links on my page: http://benniaufreisen.de/tibet-info.htm
the most roadbooks are in english. if you cant open the geocity pages in china, write me a mail.
good luck
Benni

ps: here you can see some pictures Tibet/China