I don't see why you would want to persue Pharmacy if your dream/main goal is Dentistry. A gap year will let you gain life experience that universities often look for. I personally would take a year out, get XP and level up, then reapply. I say this as why spend time studying your second option, when your first option might just need more life experience and field work in a gap year before doing the course.
That is of course only the way I see it. Your results speak for themselves, but that isn't the only thing universities take into account. I left school in 2011 with one higher at a D, now after a few years and a year at college to get my NC level 6, I'm starting uni in Sept. I waited, I did the gap year, I went back to school, and honestly, I don't regret it one bit. I needed the life XP to show that I'm capable of juggling a student and adult life, without worries. If I had the chance to do it again, I'd do it the same way, because I know I'm cabaple and ready to do such a big move, from a small town to a massive city.
I hope this helps in your decision. Good luck with everything, no matter what you decide to do, I'm sure you'll rock it!