Colleges and Universities in United Kingdom have diverse requirements relative to entrance exams. Typically, no entrance exams are required for undergraduate programs (bachelor's degree programs), except that international students are often required to prove their English language proficiency through TOEFL / IELTS. Depending on the school GMAT may be applicable for MBA program.
Undergraduate: Qualifications equivalent to two or three years in UK or overseas or A-levels.
Postgraduate: To begin a postgraduate course in the UK, you'll need to hold an undergraduate degree from the UK or overseas.