You (or more usualy your parents then you sign it) apply based on your parents income, they're expected to top them up to the full ammount.
Everything gets messed up, no one can tell you anything as invariably its someone elses data and they cant tell you about it (you, or your parents), and after all they they pay a random ammount into your bank account 8 weeks late.
It's not quite that bad, but sometimes feels like it!
If it were me again I'd take everything I could get as a loan and invest any change, but that relies on high interest and low inflation which might not be the case next year.
The loan is plenty enough to live on + pay rent etc, I used mine and didn't have to dip into any of my summer wages so actualy came out of uni with a nice cussion to tide me over untill my first payday in October.