Ash Maurya's recent post on the subject of business plans is definitely worth a read. A conventional business plan may not be your desired outcome. Check it out! https://www.linkedin.com/pulse/its-time-fire-business-plan-good-ash-maurya
Try a paragraph in written English before and more than you worry about the spreadsheet or template. If you can't tell your timed story of what you will make happen by when and why then your prettiest, formatted, proper length document may be more a work of lovely fiction despite looking like facts. A plan is not a bunch of numbers. Numbers are targets and measurements and are actually the least significant part of what a real plan to get somewhere is.
Your business plan forma really depends on how you will be using it. Is it intended as an internal document only to get team members on the same page? Or will you be going to potential investors and using it as the core of your pitch to them? Or is it for bank financing? Landlords? Marketing tool?
First you need to determine it's uses and then you can best figure out the details of format. An internal document can be more informal and shorter in length. Something for investors would need to be much more detailed and formal.
No matter how you format it, it should be a living document otherwise it is a waste of a lot of effort. Plan to update and review it regularly to keep your team focused and on the same page about where the business is going and how to get there.
What kind of industry are you into? Your business plan also depends on the kind of the industry you belong. Study the whole process of your market and know your target audience. Since you know there is no exact strategy that you can use for the entire year or season for your business. As time goes by, changes are made. We discover new things and we lost old ones. So we must be flexible on that changes. No one wants to be left behind on the latest happenings. In order to succeed, we must adopt what is current.
You can check the templates here http://www.businessplantemplate.net/