If you were still thinking of uni then it would be more a matter of UCAS points that quantity of A levels. However I doubt 2 A2s and an AS would earn sufficient.
As Buenchico says, it depends very much on the individual college as to how many courses you must take. Often their funding for your place depends on how many teaching hours they're giving you.
Is there any possibility, at this point in the year, of your switching to a different course that could be more useful to you - maybe a short vocational course at a lower level?
Otherwise, if they give you no wriggle room, I'd suggest you just concentrate on the A2s, put in the minimum required effort (or less) for the AS and don't worry if you fluff it.