I think you would be better of trying to get a part time job in a pharmacy - like one or two days a week, that way you get the experience- you'll do the healthcare assistants course and then by next summer you can look for a placement in a hospital where you'll get to do something completely different.
Hospitals are competitive and only accept 2nd and 3rd years anyway so it will look good that you are a trained healthcare assistant.
I havent even started uni yet but have worked in a pharmacy for the past year and have passed the healthcare course, and believe me its really not worth ruining your summer working 5 or 6 days a week, 7 hrs a day in a crappy boots or lloyds...you could do the same just 1 saturday a week, depending on the Pharmacist, once you have passed that course you can just asked to be trained in the dispensary....
so just chill out this summer, look for a part time job in a Boots or Lloyds -not necessarily for this summer, you can even start it in September, until next summer, and then do a placement in a hospital next summer.