Nightline is a service run by and for students. As their name suggests they are available 8.00pm to 8.00am, during term times. It is a completely independent listening, support and information service and aims to provide every student in Oxford with the opportunity to talk to someone in confidence. No contact is made with any outside agency, academic department or anyone else; you don't even have to give your name.
They don't claim to be a substitute for a counselling service but offer an anonymous service taking a friendly non-directive approach to students' problems. You can visit the website.