Germany is a healthy place; your main risks are likely to be sunburn, foot blisters, insect bites, mild stomach problems and hangovers. Tap water is drinkable.
Citizens of the EU, Switzerland, Iceland, Norway and Liechtenstein receive free or reduced-cost, state-provided (not private) health-care coverage with the European Health Insurance Card (EHIC) for medical treatment that becomes necessary while in Germany. It does not cover emergency repatriation home. Each family member needs a separate card. UK residents can find information on how to obtain the card at www.ehic.org.uk.
You will need to pay directly and fill in a treatment form; keep the form to claim any refunds. In general you can claim back around 70% of the standard treatment cost.
Citizens of other countries need to check whether there is a reciprocal arrangement for free medical care between their country and Germany.