You get out what you put in, firstly out in lots of effort at GCSE/ A level and you can go to a better quality uni with higher expected earnings and job prospects.
Secondly if you slack off and get a desmond then employers know that, the degree wont help your employment much and it wont have been worth while.
A 2:1 shows employers you have studied hard but your not quite the geeky acedemic type and your worth their attention ( 2:1 from middle of knowwhere poly maybe not so much)
A First shows employers you are acedemically gifted and/or prepared to work hard therefore you will do well ( if you can get rid of the geek image they my have!)
If you want to get value out of university get into a good one, do a sensible (traditional) course and put in the effort to do at least acceptably. Otherwise it is just a nice life experiance which although it has value is not worth £9000
My philosiophy here is slightly tainted by the fact that it will become tempting not to go for a top level uni if the fees are graduated but it would probably still say that a more expensive redbrick degree would have higher prospects but whether that matters depends on what you want to do with it.