If the medical series on TV are to be believed, doctors and nurses in hospitals spend most of their time telling jokes and falling in love with one another. But in real life, a lot of serious work happens in hospitals. Practise the words you need to talk about a hospital stay.
Polite speech often has to do with being less direct. Instead of want, say would like. Instead of can, say could or may. And to state negative information, say I'm afraid (that)... or I'm sorry, but... Practise these and further ways of being polite in English.