If English is not your first language, you will need to provide documentation of your proficiency. You may also need a visa.
English language requirements
If English is not your first language, you must be able to meet the minimum standards that are set out by the College and recommended by the University.
You can find further information on specific conditions and exemptions, as well as suitable forms of documentation, on the Edinburgh Global website.
As research involves giving presentations and writing up quickly, we would strongly recommend that your language skills exceed the minimum requirements. For the demands of a PhD we would suggest IELTS 7.0 or a TOEFL-iBT of 100.
Edinburgh Global provides a wealth of information on UK student visas, including application guidance.