Rejected, want to appeal

I was rejected from my first choice university, according to the slightly vague rejection letter it sounds like it was to do with predicted grades. Now the thing is, I'm a mature student studying my entry requirements at college and I've not sat any sort of prelims yet to give a full grade estimate, since the system seems to work very differently from school. The university did not give me much warning to acquire these predicted grades, a week tops. The lecturers I asked however did either predict me or state that they could not give an official prediction but tried to defend me to the uni by telling them about my class work etc.

So all in all I feel like I've been treated a little unfairly due to the circumstances, is it worth the appeal?

What do you mean they didn't tell you about the grades? It says their grade requirements on their course. And no, you may as well get the grades and apply next year, or go to an even better uni.