Yeah phone them directly with your situation. Although tbh you are not a mature student so it frustrates me when students want to jump on the access course train! Access courses are designed for people who have not been studying for a long time and typically have a lot more ties, not just eager to do it in a year so they are alone in a town! Some colleges however do allow students to do A.S and A2 in the same year and your A grade is fantastic and you are doing engineering so you sound like a v.competent student who could do the courses in one year. Furthermore the access course is not very thorough and ALevels are far more desireable to unis, I honestly feel you would benefit from doing A levels at your age.