wait 4 AS levels? Are you planning on taking them all to A-level then, I assume that's the point, since many start with 4, and drop to 3 A-levels.
But yes It shouldn't be that difficult. A degree, part time job & girlfriend was no issue for me, albeit of course you have more contact time during A-levels. You may only be able to see each other weekends, say stay over Friday to Saturday night, do work Sunday, then the odd weekday like go out for something to eat, depends on how that works for you. Also depends on how nearby you live.