Firstly, separate the ideas of moving away and going to uni. You shouldn't have to go to uni if you want to expand your horizons beyond your 'shite city'. You could move away and get a job but be aware of the responsibility this entails if you haven't supported yourself before.
Secondly, going to uni depends on what you're like and what it will offer you. I went to uni for a year in Edinburgh and I had no motivation and despite having interest in the subject, because at that stage in my life independent learning wasn't for me - so I dropped out. Now I've been moved out and supporting myself for 2 years, and not only have I enjoyed this immensely, it has gave me a newfound desire to go to uni and do it properly.
Get a good idea of what uni life will be like (the more perspectives the better), try to be as realistic as possible, and evaluate if you think it's the best course for you to develop on your skills and experience. If you think it's the best option, and you can adequately defend it against your own criticisms and doubts, go for it.