Must say that my Doctor is cool (and indeed prefers me to have a back up supply of meds). I explained early on that living in the sticks and needing a stash for emergency is essential. I kept a supply of spare inhalers around the place - work, car, B.O.B., home and various jackets. Also store a larger amount in my house as well as about 10 days worth in my possibles pouch. The Doctor doesn't want me running out and spoiling all the hard work in putting me back together. (Cheaper than a stay in hospital). I do rotate my drugs but I'm quite anal about these things anyway. The only thing that worries me is that the pacemaker has a battery limit. But then I can hardly just pop in a few new AA's! (Though I believe they are working on implants that are powered by body movement in the long term which is a good idea).
Just speak to your Doctor and explain what you need them for, they won't/shouldn't do anything illegal but meds are there to be used responsibly and if you have a need and it's achievable then I don't see a problem. Many places also offer a pre-ordering system where the pharmacy orders for you as regards your usage and so keeps you up to date with little or no hassles, have a word with your Doctor/pharmacist.