Pharmacy or Pharmacology? (BATH UNI)

Pharmacy is a degree that qualifies you to be a pharmacist, pharmacology is a bioscience degree focusing on drug interactions and the "theory" behind those.
If you want to become a pharmacist the only degree you should be aiming for is pharmacy.
If you don't want to become a pharmacist there's not much point in doing a pharmacy degree, so if you're not aiming for that but are interested in studying the science of drug interactions (and sometimes design/processing, although that often falls under separate degrees in pharmaceutical science/medicinal chemistry) then aim for pharmacology

I am aiming to go into medicine I cant see myself doing wither really but i have a guaranteed interview (pharmacy) or guaranteed offer (pharmacology) so I was just trying to see which one I like more. I wouldn't mind become a pharmacist but my passion is really in medicine

Honestly then I wouldn't suggest doing either. Take a gap year and reapply to medicine.
No point wasting 3-4 years doing another degree, to then be stuck either applying to GEM (which is vastly more competitive than standard entry medicine) or standard entry medicine as a graduate (where you'll need to self fund tuition fees for the first 4 years).

Do you think it would be wise to not put down a 5th option I really only want to do medicine

Not at all, in fact that's really what people suggest these days as I understand - as generally if your primary goal is medicine it's best to reapply in a gap year again rather than start another degree normally!
Bear in mind also you don't need to put your 5th option down at the same time you apply to your 4 medicine choices - you can add the 5th choice any time before the January deadline after submitting your application with your 4 medicine choices
This way you can also see what interview invites you get etc!