Some art and design will cross over into the field you're in now but you can also squeeze yourself into more of a media direction which could be a nice change of scene. Graphic design, photography etc... A lot of arts courses cram a whole bunch of practical skills into one course as well as art theory that is perfectly applicable to other areas film..even psychology. Art courses allow you to dabble in a bit of everything, or that has just been my experience. Everything from costume making to working in a film studio.
I did BTEC in art and have got onto alot of seemingly unrelated degree courses with it. If you make the intertextuality apparent in your personal statement it helps, because I knew I sure didn't want to do an access course or something like that.
Portfolio wise you want to demonstrate an understanding of/proficiency in a wide range of media, digital and traditional. You want to demonstrate anatomical knowledge of humans and animals through life/figure drawing as well as doodles from your head. Your architectural knowledge gives you an edge with visualizing shapes, spaces, distance, proportion and the types of line that are pleasing to the eye.