There is no part of the immigration rules which says that a student visa holder cannot leave the UK during their studies. However it is very important at all times to be following the university attendance and engagement policy.
The attendance and engagement policy is managed and checked by your academic faculty. The university Retention & Success Officers can advise you on when you must be in attendance, and how to make sure you are following the engagement requirements. You can find their contact details here: Student Engagement | Student Services | University of Greenwich Not following the university attendance and engagement policy can eventually lead to withdrawal from your programme of study, so make sure at all times that you understand what your attendance requirements are.
Absences from the UK can sometimes have an impact on future immigration applications. You also need to consider whether you should carry some evidence with you when you travel, showing that the university does not object to your period of time away. You’ll find more guidance on impact of travelling and immigration advice here: Travelling in and out of the UK | Visas and Immigration for study in the UK | University of Greenwich
If you still have complex or confidential questions, please contact the International Advice Service by completing our self-referral form.