It depends on the level and route, but common essentials repeat. For UK-campus postgraduate taught applications, Heriot-Watt says the only required upload to start review is your academic transcript, and it recommends adding your passport photo page (for international students), degree certificate, and evidence of English; you may later be asked for items like a personal statement, CV, academic reference, or a digital portfolio (for some design/textiles courses). For undergraduate direct applications, the initial required document is typically your transcript/marks sheet, with similar recommended additions (passport page and English evidence) and possible later requests (statement, CV, reference, portfolio).
In research-heavy paths, documentation can be more “project” focused: Debabrata Dutta highlighted the importance of strong referees and proposal strength; alongside “strong letters of recommendation,” his story repeatedly points to the research proposal/supervisor fit as a decisive part of scholarship-style applications.