^^^ Pharmacists are allowed to sell large quantities of paracetamol, even without a prescription, if you can provide them with a valid reason for doing so. (i.e. the '2 x 16 tablets maximum' rule doesn't apply to sales from pharmacy counters).
When I was due to go in for my prostate op, the nurse told me that I should stock up on both paracetamol and ibuprofen, ensuring that I'd got enough to last me a couple of weeks. I explained that to the pharmacist in Morrison's and he was happy to provide me with several big boxes (each containing 48 tablets) of each.
As it turned out though, I didn't need to take a single painkiller after my op, so I've still got a cupboard full of them!