The UK and Austria have a reciprocal emergency healthcare provision agreement between them, and on production of an E111 you can expect to receive free treatment in state hospitals.
You should however still arrange for comprehensive medical insurance prior to travel in order to have sufficient cover in the event of illness so that your repatriation expenses are covered.
While no vaccinations are required to visit Vienna itself, should you be travelling into the countryside during the summer, you should take precautions to avoid Tick Borne Encephalitis which us is a problem in wooded areas.
