The current statutory minimum is 4.8 weeks paid annual leave (that's 24 days paid holiday if you work five days a week).
You do not have a statutory right to paid leave on bank and public holidays. If paid leave is given on a bank or public holiday, this can count towards your minimum holiday entitlement. There are eight permanent bank and public holidays in Great Britain (ten in Northern Ireland).
So, as you have been told that BH count towards your paid holiday entitlement then;
GB = 8 BH + 16 days
NI = 10 BH + 14 days
http://www.direct.gov.uk/en/Employment/Employe es/WorkingHoursAndTimeOff/DG_10029788