You are entitled to 5.6 weeks of holiday time with pay - at least 28 days paid holiday for employees working five days a week. This is worked out on a pro-rata basis for part time workers.
You might have to take public holidays such as Christmas, Easter and Bank Holidays from your entitlement but this should be set out in your contract or written statement. Employers may specify exactly when you can take your holiday.
When you leave a job, you should get paid for any holiday you have not taken. You will continue to be entitled to your holiday leave throughout any ordinary and additional maternity leave and paternity and adoption leave.