Namasta Sir Me (Nepali ) and my friend(from Uk) we want to travel to Tibet.

Dear sir
Me and my friend we want to travel to tibet on the first of October for 12 to 15 days. He is coming to nepal on september 27 and we will travel to Tibet on october 6th. So What types of Visa we can take (ordinary , Urgent or Extrem Urgent) with in 10 days . And how much for nepali and Uk citizenship for 15 day visit in Tibet. Please i am waiting your reply.
Rohan