Yes, IBAN is a European idea.
All the info you need is on the web if you search for it:
http://www.apacs.org.uk/IBAN/iban/default.html
The IBAN is a set of characters appended to the sort code and account number to identify the country and bank that the money is being sent to.
UK IBAN numbers are composed of:
Country code, check digits, bank code, sort code, account number.
e.g.
GB 99 NWBK 123456 12345678
or
GB 12 CPBK 089299 12345678
Sort codes are 6 digits long and always numberical.
As a rule of thumb, the first 2 digits tend to indicate the bank, the remaining 4 often narrow it down to a particular branch.