Tell your parents its your choice and what do they know? It IS a great uni any fool knows that, loads of people would kill for the chance to go there, and who cares about the reputation?! It's not about that, it's about what you can show you have learnt/how you have grown.
I went to comprehensives, did mickey mouse A levels (psychology, business studies, RE) and I still got onto a Law and Business degree at Warwick (about 30 applicants a place).
I then quit warwick after a year, but still got 6 unconditional offers from wicked unis...because I was able to show what I had learnt and how I had grown, go where you want to go, dont get hung up on reputation (durham has a fantastic reputation anyway). According to these latest world league tables, which many commentators are claiming to be a lot more accurate/representative than the ones we currently use, uni of sussex is meant to be one of the best universities in the world...just go where u wana go.
This reminds me of something that pissed me off the other day, my sisters friend wants to drama for GCSE, and her mum wont let her because "universities dont care about drama gcse, you're better at academic things, the people who do drama gcse are the people who cant cope with proper subjects". I've never heard such a massive load of crap in my life...stupid old people talking about things they dont know about.