Can I work or study on a Marriage Visitor visa?

This visa is strictly for visiting to get married or form a civil partnership, so taking employment or enrolling in study is not permitted.

Very limited business-visitor type activities connected to an overseas job (such as attending a meeting) may be allowed under the general visitor rules, but taking a UK job or a course of study is not. If you need to work or study, you will need a different, appropriate visa.