Work experience will look good on your UCAS application but also gives you a unique advantage over other candidates come your interview.
Try to link in your experience to some of your interview answers. You can probably write down five questions you are guaranteed to be asked at any interview... try to think up model answers for them. Encorporate your "unique selling points" (like your work experience) into these answers to show yourself off!
I would recommend you get a total of at least one week's work experience. Ideally, two weeks. I can only give you a guide here because I am not an admissions tutor. However, a day here or there (16 hours is equivalent to 2 working days roughly) does not really constitute much work experience in my opinion. Also, I certainly doubt you have exhausted your learning in just 16 hours - if that's the case, you aren't asking enough questions!
Think about what sets a pharmacist apart from the other members of the dispensing team. And no, I don't mean just the fact they have a degree. Think about their responsibilities (as mimsicle mentioned above) e.g Clinical Governance lead, advanced and enhanced pharmacy services etc and how these make pharmacists a vital part of the NHS. Showing you've done a bit of research proves you're interested in the profession and you are willing to go that extra mile - a very useful asset for a student.
Ask to read their Pharmaceutical Journals too (if they have them... many pharmacists stock pile them as part of their RPSGB membership). This is something else you can write on your UCAS form e.g I regularly keep up to date with current affairs in the pharmaceutical industry by reading the PJ etc etc.
Finally, try to enjoy your experience. Ask the pharmacist about their time at university and their careers. Get a good feel for the profession and the environment you will be working in when you are older (hopefully!).