unashamedly copied from a pdf on the web:
Payment methods
Many agents/landlords ask students to pay all of the
rent in advance in the form of 12 post dated cheques. You
should avoid this if possible, post-dated cheques can be
presented before the due date inadvertently and if you
have insufficient funds in your account you will then be
charged by your bank for bouncing a cheque. You could
ask your landlord/agent if they can set up a standing
order instead. Good agents/landlords would not have a
problem with this. Some premier agents may even have
a have Direct Debit facility in place. This is the easiest
and most effective way of paying your rent as it takes
the hassle of remembering to pay away from you.
Whilst most agents will still accept cash payments the
safest way to pay is taking advantage of credit/debit card
payment facilities. Remember to check as to whether
surcharges apply. That way you are not carrying around
large amounts of cash and all payments are backed up
by your bank statement as well as your receipt!
from here ("Cardiff's letting agent")
http://www.keylet.co.uk/website/_documents/studentguide.pdf