work permit required for student visitor to do voluntary internship?

[cvv]

Hi , My daughter is an Indian national and undergraduate student in India. She would like to spend her holidays in UK in the summer and while on holiday on visit visa she wants to utilise her time to do a summer internship related to her academics and college curriculum in the UK voluntarily for a period of 3- 4 weeks. Does she need work permit for the same even if she opts to do it without expectation of any remuneration?
What category of Visa she has to apply for?

[CR001]

She would need a visa and an HO approved sponsor.

She cannot do any work, paid or unpaid or voluteering, while in the UK on a visitor visa.