https://registryservices.ed.ac.uk/immigration/applying-for-visa/other-visa-types/standard-visitor/who-needs-to-apply
Who needs to apply for a Standard Visitor visa | Student Immigration Service | Student...
Visa nationals must obtain entry clearance as a Standard Visitor. Non-visa nationals can seek entry at the border with an ETA. Maximum visit of up to 6 months.
apply for astandard visitor visa