When you come through border control at the airport, a border control officer will stamp your passport. This stamp shows your date of entry into the UK, so it is required for registration at the university if you are entering with a student visa.
Travellers from some countries (Australia, Canada, Japan, New Zealand, Singapore, South Korea and the USA) are likely to be directed to electronic passport gates (eGates or ePassport gates) which are also used by UK, EU, EEA and Swiss citizens.
If you will be arriving to start your course in September, you may find there are dedicated student lanes at some UK airports so watch out for these when you arrive.
UK government guidance