with mine, i jst accounted for all my bills (gas and elec i guessed from what my previous employer paid on hers) and then how much i needed to take from the business to keep myself afloat. i accounted also for a junior @ £100 a week, although I didnt take one on at the beginning. So I just added together....
rent
rates
wages of junior
wages of myself
elec
gas
phone
pdq charges
accounted for £50 a month printing
advertising (again £50 a month)
i cant think of what else. worked this out per month, then divided it down til i knew how much i needed to clear per week and day.
I planned small, but i also knew that i would be disappointed if by the end of the first year i hadnt taken on any other staff.
the way things have worked out for me is totally different than how my plan was (luckily better)
have u been to business gateway/link?