The Student Loans Company organise the payment of fees and who you can get a student loan from. Don't forget: if you don't apply for a loan, you won't get one! If you haven't applied for a loan, but get short of money, you can apply for the loan part way through the year.
The contact details vary depending on where you are from:

England
Student Finance Direct: 0845 607 7577, Monday to Friday 8.00am to 8.00pm and between 9.00am and 5.30pm at weekends)

Wales
Student Finance Wales: 0845 602 8845, Monday to Friday 8.00am to 8.00pm and between 9.00am and 1pm on Saturdays)

Northern Ireland
Student Finance Northern Ireland: 0845 600 0662, Monday to Friday 8.00am to 8.00pm and between 9.00am and 5.30pm at weekends)

Scotland
Student Awards Agency for Scotland: 0845 111 1711 between 8.00am and 6.00pm (4.30pm on Fridays) from June to October, and 8.30am to 5.00pm (4.30pm on Fridays) from November to April.

Other EU Countries
Information about EU Student Finance on the Directgov website.
More information on funding is available at Directgov.