Just because accommodation applications open doesn't mean that you need to immediately apply. They are not going to 'run out of rooms', accomodation is not going to 'fill up', and you are not going to be homeless.
Think about it. The vast majority of applicants will not even have their 5 decisions yet, and may not until May, so what is the urgency. Rooms are not actually allocated until August - because a whole heap of those applying for accomodation now wont be going to that Uni at all. And ALL Unis know this.
Come August, many of those holding Firm offers wont get the grades and will be rejected, or will defer, drop out, change their minds, go some where else in clearing or just not turn up. Hundreds of them. Their accom applications can all be binned. Only then will any Uni know who is actually going to be there and will start considering who will get specific rooms/halls.
So stop panicking. You do not need to apply right now. It isnt 'first come, first served' (whatever that Uni tries to tells you) and when you apply will not determine which room you get. Just because you have applied for X accomodation, does not guarantee that you are going to get that - if it did then they wouldn't bother asking for your second, third, fourth etc preference would they. And having a fancy ensuite is not going to mean your degree course interests you any more or that you will get a better degree grade. And 'going to Uni' is about far more than your bedroom so try to get a sense of perspective about this.