You can stay in the UK for up to 6 months as a Standard Visitor. Nationals of EU/EEA and many other countries can come as a Standard Visitor without a visa. (Note: Irish citizens can move freely and indefinitely in the UK; no special permissions are required). Some nationals will need to apply for a Standard Visitor Visa. You can check here whether you need to apply for a visa: https://www.gov.uk/check-uk-visa
The immigration definitions of ‘study’ and ‘work’ do not apply to sitting or serving at a Vipassana Meditation Centre. Therefore, under ‘What are you coming to do?’ you should select tourism.
Although within our centres we use the terms ‘student’, server’, ‘course’, ‘volunteer’, we cannot expect border officials, or anyone who is not familiar with our organisation, to understand that these terms are not used in the conventional sense of study or work. To avoid confusion, it is better in this context to use the words ‘retreat’ instead of ‘course’, and ‘meditator’ instead of ‘student’ or ‘server’. Meditation is a mental exercise, a spiritual pursuit undertaken for self-development and well-being, and in immigration terms it is a tourist or leisure activity. At Vipassana centres, the ‘students’ and ‘servers’ are all ‘meditators’, whether sitting for 3 or 10 hours a day. They are all practising the technique, albeit following different daily schedules. Serving is an integral part of the practice. The meditator is primarily serving oneself, and is using service to develop good qualities and strengthen their own meditation practice while living by the centre's rules, timetable and discipline.
In case you are questioned at the border, we can provide a letter of explanation when you have a confirmed place on a course or service period, and you can show this letter to the immigration officials if necessary. It includes the above points and illustrates why someone coming to a Vipassana centre is a genuine visitor under UK immigration law. You may also find it helpful to use this letter when applying for a visa.