I got a job

So after a couple of years of searching (thanks lack of jobs in this town) I finally got a job, not a particularly illustrious one. Checkout work in fact. At Sainsbury's. But a job nonetheless.

Unfortunately I obtained the position a mere month before I'm due to ship off to university (results are out on the 14th and my Uni start date is the 7th of September) so now I'm at a bit of a loss what to do when the time eventually comes (if I get my results), do I:

a.) Tell them I never expected to achieve my results and I wanted to keep my options open. Ask if there's the possibility of me transferring to a Sainsbury's in my University town.

b.) Apologise and say that due to circumstances beyond my control I am no longer able to keep the position and just leave.

I know that I should have said something in the interview (I did mention that I'd only just finished college in June and that I was doing A levels) but to be fair it completely slipped my mind. I would really like to be able to continue working when I go to Uni so for me the first option looks like the best, if at all possible.

If any of you wonderful people have advice or alternative options it would be most appreciated because I feel a bit rotten just upping and leaving after a month. Ta muchly.

edit: just talked to the manager of the uni-town store and head office, they both said I could do something called a dual store contract. I would work at Uni during term time and at my current store during holidays. Ultimately, he said, it was up to whether or not my store would allow it. If they weren't happy about it I would have to quit and reapply to the new store.

Also my results are out on the 14th, cue panic mode.