accommodation in brighton and sussex medical school

If that is what the terms of their accommodation offer is then yes, you would not be guaranteed accommodation if you do not firm it.

That is pretty standard across many universities. In practice ther is a fair bit of movement when it comes to confirmation of exam results when people do or don't take up their places.

So it doesn't mean you will necessarily be homeless, just that they cannot guarantee it,and you may have to look to private provision.

Some unis have a lot more pressure on student accommodation than others, Manchester, York, and Bristol for example. Not sure about Brighton. But do check what the pressures are wherever you apply and knowing and adhering to the guaranteed accom terms is important.