The University has a formal procedure for handling withdrawals and the subsequent refund of tuition fees.
If you withdraw formally before 1st December in your first year of study you will receive a full refund of all amounts paid to date for tuition fees.
If you withdraw on or after 1st December in your first year, you will be liable for one-third of the annual charge for each term started.
The procedure is slightly different for students who have a Tuition Fee Loan from Student Finance England.
You can find more details here.