If a document needs to be developed that requires input from other disciplines_Finance, HR, Property & Facilities, Marketing, Procurement/Supply Chain_ then most likely you are looking at a team building effort to get the job done. In any event, don't look at the task as only as a roadmap that leads to a profitable product or enterprise. Business plans are a great way to build team buy_in, force a thorough review of options, define objectives, establish benchmarks to judge performance, and help arrive at a plan_of_action. Ultimately, it can lead to a Project Management approach to implementing a plan and that can be as involved and detailed as is necessary.
Track Your Progress _ A business plan should not be forgotten about once the catering business has launched. Refer to the plan regularly to see if you are on track to hit the goals that you set out. Make changes to the plan as you go so that you always have a plan in place for your business going forward at least two or three years.