One Year Access to HE + A-Level Maths

Hello everyone, I won't bore you all with the reasons behind why I am in this situation, but I am keen to see if anyone else has done this and how much hours/hard work I would have to put in, or if it is even possible.

Effectively, I am looking to do Architecture at University. I am thinking of sitting an Access to HE in Art & Design, alongside an online intensive A-Level Maths, I also intend to work around 16 hours a week alongside this.

I am just wondering how difficult this would be, what the hours involved are, and if anyone else has gone this route before? Right now, I am assuming the Access to HE would be around 20ish hours a week (16 hours in College, 4-6 hours a week independent study and assignments), the A-Level Maths would need around 10 hours a week and then I would be working 16 hours a week alongside it, so about 46/48 hours a week total, which isn't too bad as it's only a little over a regular full-time job, but then there's also all the travel involved.

Obviously, this all becomes a lot easier if it turns out I don't need A-Level Maths. However, I have seen conflicting claims on this, some say you do, some say you don't. Would you get away with an AS Maths instead?