Chinese currency available from local bank?

Can I purchase Chinese currency from my local bank and can I sell unused currency when I return back to the bank? If so, has anyone any experience regarding the rate of exchange given whether good or bad as some banks have a different spread on unusual currencies?

Bank of Ireland do a preordering service,if you are a customer.

http://personalbanking.bankofireland.com/bank/international-payments/foreign-currency/