As you are already in the UK, you can forgo most of the steps international students take at the start of their course. You most likely already have a bank account, registered with a doctor and, if required, the police, have a phone and sort of know where you are going, or at least where to find out. You will still need to enrol, go through induction and meet your tutor, though. In these first few days, you will meet your tutors and new friends, get a brief introduction to the course and university and you will recieve everything you need to start your course, such as student card and reading list. If you are doing a postgraduate degree, then you are unlikely to have secured accommodation in the halls, so you should have previously arranged a private rental.