The currency of Tibet and China is the Yuan (CNY), also known as Renminbi or "people's money".
One Yuan is divided into 10 Jiao (popularly known as "mao") and then 100 Fen. On 9/4/2013: 8.15 Yuan = 1 Euro. For the current exchange rate please visit http://www.oanda.com/
Euros for example can be easily exchanged at banks, exchange bureaus and at hotel receptions. This only applies to the larger towns however, such as Lhasa and Shigatse where you can also withdraw using the Bank of China atms.
Pocket money: The recommended spending money is a minimum amount for meals, drinks, optional excursions, entrance fees, airport taxes and gratuities. The amount you end up spending is of course highly dependent on your own spending habits, souvenirs are therefore not included.