OK. We can go about this a couple of ways:
1. See what Biomedical Science courses you might be able to access with just the BTEC Level 3 Diploma in Applied Science (worth 2 A levels).
2. See what additional qualifications might be an option to run alongside that BTEC.
For option 1, let's focus on universities which state their entry requirements in terms of UCAS points. I realise that it's a tad early, but do you have a target in terms of grades? If you were to obtain D*D*, that would get you 112 UCAS points. London Metropolitan University will accept 112 points for "Biomedical Science - BSc (Hons)", and also state that they accept "BTEC Level 3 Extended Diploma/
Diploma" (
details).
If D*D* might be expecting too much, then the same uni want only 32 UCAS points for their "Biomedical Science (including foundation year) - BSc (Hons)" (
details). You'd get 32 points from grade PP. Of course, this approach adds an extra year to your degree. This would be more expensive that adding an extra year to your college (which you've said you'd rather not do) - because of uni fees and accommodation costs.
For option 2, would you have any capacity to study a BTEC Extended Certificate (worth one A level) alongside your existing BTEC - or even an actual A level. Does the college offer either of those options? Subject-wise, perhaps Applied Human Biology (if a BTEC Extended Certificate) or Biology / Human Biology (if an A level).
Ah, so you've not actually started college yet, then. I'm that case you'd be much better to find a college which offers a BTEC Level 3
Extended Diploma in Applied Science. That's worth 3 A levels, which is what most unis are looking for.