The costs for electricity (so even if you cook via electricity) and for water consumption are included in the service costs, so you already pay these with your rent. You also already pay for your heating costs.
You will have to find a supplier by yourself for gas for cooking.
Tip: ask your housemates! There is probably already a contract through one of your housemates.
The settlement of the service costs usually takes place before July 1 of the relevant year. For more information about your heating and service costs, click on the links below.