So you're a first year med student?
If you're doing this for extra money or because you want to then that's fine go for it. Just... don't feel you need to do this, is all i wanted to say. You will learn all of those things in clinical years. Focusing on your current studies will probably be the best way to make yourself a better doctor, and getting prizes/getting involved in research will be the best way to improve a CV. Being understanding to nurses/other staff doesn't require years of penance in a HCA role alongside full time medical studies. It just requires you to be a nice person.
But like i say, if its just something you want to do then go for it.