I thought I would share what I have just found out about the KCL accommodation policy, hoping that it might help some of you.
I quote the email I got in response to my question.
"You can make changes until we begin the process of allocating rooms to
people. As such, it would be preferable if you could make your changes
before next Monday the 15th of August, as the application system will be
taken offline at some point next week. You can either make the changes
yourself on the online application system, or we can do it for you if you
provide us with a list of your new preferences as soon as possible.
Here is a brief tutorial on how to make the changes on the online
application system; sign in to the system, click on the 'Application' link
on the left hand side of the page, and then click on the 'Room / Plan
Preferences' link. From here you must select '2011 Entry New Undergraduates'
from the drop down menu, and then click on the underlined number next to one
of your hall choices. You can then edit the ranking of this hall choice.
Repeat this with the different halls until you have a list of choices you
are happy with.
Editing the rankings of your hall preferences now will not disadvantage you
when it comes to how we considery our application, and you will remain an
"on time" applicant."