The entitlement, and the confusion around it
Statutory leave is 5.6 weeks a year. For someone working five days a week that is 28 days, and an employer may count bank holidays within it rather than on top of it — which is where most disagreements start.
Part-time workers get the same 5.6 weeks pro rata. Workers with irregular hours accrue leave as they work, and the rules here changed recently enough that older guidance is unreliable.