FWIW, my hubby, an Aussie who moved to the UK after he finished uni doesn't have to begin to repay his Aus uni debt till such time as he is resident in Aus again permanently. But in the meantime, the interest will be stacking up and he'll have a chunk to pay off when he finally moves back. No matter how long he is gone for, unless he never resides permanently in Aus again he will have to repay that student debt at some point. I think the UK has something similar.
I'd not run out on a student loan or avoid paying it if you are obligated to do so. Fair enough, if you don't have to repay it if living overseas, don't, but should you return to the UK to live, you should be prepared to repay what you owe.