Unless the college has rules about you having been out of education for a period or being over a certain age, there should be nothing to stop you applying.
Contact your local university offering the access course, explain your situation. Find out who the awarding body is and the progression options. It may be that this more like a foundation year, than a traditional Access course, successful completion may lead to place on a degree course at that university. It may or may not be accepted by other unitersities. You would be best to apply and secure your place, so you have an alternative option.
If you secure a place on the Access course, you will get your AS results before you start the course. If they are better than expected and you can resolve your A level study issues, you would be better off finishing off your A levels. Employers and universities prefer A levels, you get UCAS points. Consider getting a tutor, if you do go on to A2. You probably only have 4-5 months of study time left, the rest is revision. Remember, you can always retake your AS exams in January if necessary, you do not have to wait until next June.
If you decide to go the Access course route, make sure all the universities you want to apply for accept it. Not all do, this can be more of an issue with science, rather than arts subjects. Think about what you want to do after your degree. Do your potential employers use A level grades as a filtering tool. Will you be able to gain work experience during your studies to to enhance your CV?
Make sure you check what your fee status will be if you decide to do the Access course.