- Serial Entrepreneur in the High-Tech & Service Industries,
- Expert in European Business Development,
- VP International at NewCom Inc (Nasdaq listed),
- Founder of Easy Consulting,
- VP @ High-Tech Business Club,
- Founder of Portail des PME,
- Investor @ Clean du Bouquet,
- Co-Founder of Entrepreneurs and Co,
Business plan is a document that spells out a company's expected course of action for a specified period, usually including a detailed listing and analysis of risks and uncertainties. 
For the small business, it should examine the proposed products, the market, the industry, the management policies, the marketing policies, production needs and financial needs. Frequently, it is used as a prospectus for potential investors and lenders.
In a nutshell, the business plan should clearly explain the what, why, when, who and how of the project. It should be a comprehensive explanation of the opportunity, the people involved, the money required to implement the plan, where it will come from and what financial results the opportunity is likely to produce.
A written document that expresses the corporate vision about the future of the company. To succeed, your vision must be global. To be credible, your business plan must rest upon the success to date of your private company. 
A schedule of proposed business activities and aims over the next year or other specific period. The plan is based on projected figures for sales, turnover, profit and other factors and can be used to motivate individuals within a business and to measure actual performance. Many banks want to see a business plan before they will agree to lend a business money.
Now the question is : Consultant or Software ?
- a consultant will give you a vision and his expertise,
- a piece of software will give you a suite of tools,
A combination of both of best worlds may be an idea ;-)
At the end of the day,The plan communicates the business elements to lenders and others, provides the basis for managing the business, and provides a yardstick by which progress may be measured and changes evaluated.