Help!!! A Level Sociology + BTEC L3 Extended Diploma?

So basically I messed up my AS year due to poor mental health and decided to do level 3 extended diploma in Health and Social Care this year. I'll be getting three Distinction*s overall at the end of my two years, this is a fact by this point.

Three Distinction*s is the highest grade possible to achieve on a BTEC course and is worth the same UCAS tariff points as three A*s at A-Level.

My one goal is to make it to the University of St. Andrews and do the MA (Hons) Psychology course there. They ask for BTEC extended diploma grades of D/D/D to D*/D/D, so I'll already meet the entry requirements with my D*/D*/D*.

They also suggest to do an A-Level along with the BTEC Extended Diploma to make my application more competitive, so I am considering fast-tracking A-Level Sociology using OpenStudyCollege.

The A-Level Sociology course costs £800 and I have no problem paying that provided I will actually get into St. Andrews at the end of next year. Basically I'm asking if anyone has ever heard of St. Andrew's accepting applicants with only a BTEC level 3 Extended Diploma? Like what are the chances of me getting in with D*/D*/D* and then maybe an A or B in A-Level Sociology? Is it possible?

I'd appreciate any information or support.