It all depends on what is in your contract of employment but do remember part time workers must not be treated less fairly than full time workers and full time workers maximum entitlement is 28 days paid holiday per year (X 5.6 for a five day week) and pro-rata for part time workers, people working 6 days a week are restricted to the 5 X 5.6 calculation = 28 days. A myth is that bank holidays must be in addition to holiday entitlement, they must not and the maximum 28 days can include all bank holidays though most employers give bank holidays in addition to holiday entitlement.
If you work two days per week you are entitled too 11.2 days holiday per year (2 X 5.6 = 11.2 days) which many employers would round up to 12 days per year, which could include bank holidays but normally, would not.
To ensure part time workers are treated no less fairly their holiday entitlement and bank holiday pay must be paid in the same way as full time workers but pro-rata.