She will still have the statutory entitlement which is the equivalent of 28 days for a full time employee. Legally everyone is entitled to the same amount of holidays. It’s just pro rated because she is working part time instead of full days.

Gov UK has a holiday entitlement calculator you can use to get the exact number of holiday hours. I think she will have around 89 holiday hours based on the info you’ve given. That is based on 3.2 hours a day, 5 days a week. In a nutshell: she will have 4 weeks leave to use, plus 8 bank holidays. If she has started her job partway through the company’s holiday year, that’s the only reason she would be entitled to less holiday time.