I guess I don't understand the concept of a digital spreadsheet for this application.
As Brian mentioned above, about the only use I can come up is a way to format the information that you plug into the columns. I really can't imagine finding a spreadsheet that could provide the figures for rent, equipment costs, etc. Every business plan would have different figures, depending on way too many factors to standardize, imo.
As far as "allocating" fixed and variable costs... Your fixed costs are just that: Rent/lease, wages, utilities, insurance, telephone, etc. Your variable costs fluctuate mostly on volume of business. (My variable costs are green beans, cups, lids, straws, bags, etc.) The driver of the variable costs would be be different levels of forecasted sales.
If I were you, I'd add up the cost of setting up the shop, (equipment, furnishings, initial supplies, etc.) to come up with a number representing the capital investment needed to launch the business. Then I'd lay out all of the fixed costs associated with the month to month operation of the business (rent, utilities, telephone, bank loan, etc.) Its then possible to calculate a sales/revenue level necessary to break even by adding the variable costs associated with specific levels of merchandise sold to the fixed, monthly costs.
As a simplistic example, lets say my fixed costs are $2,000/month and my variable cost is roughly $5/lb of roasted coffee sold. Revenue is $15/lb. If I sell 200 lbs of coffee/month, my revenue would be $3,000. My variable costs would be $1,000. Total costs for the month would be $3,000. So 200 lbs. of coffee sold for a month would be my break even point.
If I manage to sell 500 lbs. of coffee per month, my revenue would be $7,500, while my variable costs would be 500 lbs. X $5, or $2,500. Variable and fixed costs would total $2,000 + $2,500, or $4,500, leading to a profit of $3,000.
Hope this helps.
lw