When you start your programme, you will be asked to bring your visa and passport for an ID check. The University will check your ID (to ensure you are who you say you are!) and will also check that you have a valid visa to study in the UK. It is important that you do this check, as you will not get your student ID card until it has been completed. Your induction pack will give you more details of where and when you have to go for your ID check.
During your studies, you may also be asked to attend another check of your visa and passport. This usually happens twice per year and you will be emailed about this. It is nothing to worry about and is simply a part of Middlesex University's obligations to UK Visas and Immigration. The check takes about 5 minutes and it is very important you attend, as you may be withdrawn if you don't.