Surely you're not in any way a re-sit applicant? You're not re-sitting anything, you're doing totally brand new stuff o___O That's like calling somebody who takes a gap year a re-sit student, the only factor is time.
Re-sitting is about people who weren't capable of getting the grades for one reason or another on their first attempt at an exam. There are some legitimate reasons why people don't get the grades first time around, but generally it's viewed as a poor prognosis in terms of how you're going to be able to cope with medical school exams, which are more intense and much harder, when you've had some issues with A Levels. That's the rationale behind excluding re-sit candidates, but you are in no way in that sort of situation so I can't imagine it would apply to you in any way, shape or form.
I'd just apply normally. Unless I've totally mis-understood you and you failed or didn't do as well as you wanted to in either Biology or Chemistry and so resat that specific exam, then you're barking up the wrong tree with this one, there's nothing to worry about.