While these are easily available online, some of them are way better than the others. A lot depends on the approach that goes into writing the business plan.
Internet Public Library - The Census Data and Demographics (ipl.org)/: An especially useful site that has links to information about countries other than the U.S.
Financial Plan - What is the anticipated income? What are the cash flow projections? What is the anticipated budget over the next 3 years? What is the break even point? When is it anticipated to be met? What funding is needed and where will it come from? What funding is currently available? What collateral is available? What is the net worth of the principals, if applicable? Possible Data Sources: accountant; accounting software; Small Business Administration; Small Business Development Center; SCORE; banks; venture capitalists.
The best place to find web templates is to search on the Internet. There are many sites to search templates and they frequently provide good supplementary details and technical support. You can regularly see a sample of the template you are taking into consideration.