I've just found the email I got about accepting the Tenancy Agreement, hopefully this will be a better worded version of what I am saying (and I apologise for saying 10 days earlier):
"This email contains important information about your allocated room in Halls and requires action on your part. If you do not take this action within 7 days of the date of this email you may lose your allocated room.
We are pleased to offer you accommodation for the 2011-12 academic session. Please click here to view and accept your Residence Agreement. You must also read the Residence Conditions and other relevant information.
If you wish to accept your room allocation, please follow the instructions once you have logged-in. You will also need to pay a deposit of £300, so please make sure you have your credit/debit card with you. If you are an international student who has already paid a £300 application fee, you will not need to make any further payment, but you still need to tell us that you’re accepting the room you have been offered. Please also let us know if you don’t want the room you’ve been allocated after all.
You must accept or decline the room within 7 days of receiving this email. If you accept the offer of a room you must pay the deposit of £300 as requested."