It isn't easy. My boyfriend and I have been together almost 6 years, and have lived in different cities for 3 of those (he's in London, I've lived in cambridge, and now nottingham). We see each other most weekends, or sometimes during the week, if i've no classes.
I think there are some things you have to be aware of - by having a LDR, you will miss out on things. You will be travelling around the country while other people stay in halls, are nice and settled, and you may feel like you're not quite 'part of the gang'. This means two things:
1. You need to be prepared to be more outgoing when you're actually at Uni, and maybe make a bit more effort to make connections with people.
2. You and your partner have to have EXCELLENT communication. Both of you will feel at some point like the other is neglecting them for the sake of staying at Uni and going out. Both of you need to be aware that going out, making friends etc is important, but equally so is your relationship. You need to be honest with each other, and yourself, and make sure that you are not being too clingy, and also that you are showing that you trust each other. If you don't talk, these feelings will fester, and you will end up splitting.
LDRs are hard - I often feel like i'm never quite settled in one place. They can work, but you have to work at it - and often people don't want to. that's not necessarily a bad thing - that's often down to the strength (or rather weakness) of the relationship, and can end things sooner instead of letting them just trundle along in mediocrity. Equally, the distance can make you complacent, and let the relationship go stale when it should have worked - make the time you have together special. leave the washing up, don't do the housework - make plans and do something nice. EVERY TIME. Not necessarily expensive meals etc etc - just little touches; candles with dinner, make a nice dessert etc.