Hey, I have quite a bit of insight in pharmacies.
Firstly, you can't get a licence to open your own Pharmacy, they just recently siezed that loophole. The only way you can is if there is a need (if for example, a new town is being constructed etc)
You can only purchase a pharmacy, and they're going for at least £500,000 to a million.
Working as a locum is becoming increasingly hard because there are a lot of pharmacists around at the moment. The "pharmacist" magazine state that by 2020ish, there will be an excess of 20,000 pharmacists - without jobs. As well as there being limited number of jobs, they will be with a lower pay. A lot of pharmacists are coming over from abroad, and are a lot cheaper to hire so independent pharmacies prefer to take them on for obvious reasons.
So the pharmacy career is looking really tough, and I'm sorry because you've probably been looking forward to it
This of course does not mean you shouldn't go for it, if you want to by all means do. It'll just be difficult!
Now for med, if your A level grades meet the entry requirements, and you do well in your UKCAT and have sufficient work experience, you can apply for medicine at undergraduate level. Your GCSE's will play a part if you apply at Oxbridge, or UCL as I understand it so for the rest you'll be fine
If you do pharmacy however, and then do medicine it will not be a waste at all. Infact, you'll be an absolutely fantastic doctor because you'll have a greater insight on medications than most doctors would. It would definately benefit your career, and having pharmacy as an undergraduate degree will also aid your medicine application.
Hope this helps