On a Nationwide statement they are also on the right, under "Receiving an International Payment?". 'BIC' and 'Swift Intermediary Bank' are not the same on mine.
Ask your Bank or just check their website. SWIFT codes look like BARCGB2LA . YOUR IBAN should be on the statement and will incorporate your account number. (For UK banks should start GB)
You do not need to know the intermediary or correspondent Banks, its up to them how they send the transfer.