Assuming you are talking about a Magistrates' court case, if the Bench is considering anything other than a fine or a discharge a pre-sentence report will be required.
Sometimes this can be done at court on the day. This depends on the type of sentence under consideration (it cannot be done if custody or anything other than a straightforward community order is being considered) and the availibility of probation staff at court. Otherwise an adjournment will be necessary, usually for about three weeks, so that the report can be provided.
The situation is similar in the Crown Court, though judges sometimes exercise some discretion over whether they need a report or not.