As above - if any Uni is doing this, it is 'pressure selling' and forbidden by the UCAS agreement.
Please forward the email to UCAS asap. This wont impact your offer / place, it will just mean that all applicants can make a calm, sensible decision about where to go Firm without Unis playing silly games..
And since a) they wont allocate rooms until after Results Day, b) thousands of those who go Firm/apply for housing wont get the grades, will defer, cancel places, drop out, not turn up etc etc, and therefore 'their rooms' are back in the mix, there is actually no big problem with getting accommodation that means you have to apply right now.
WAIT for all your offers, and then think carefully about what you want to do and where you want to go.