Spreadsheet for small businesses - forecasting/budgeting/target setting

I run an accounting firm
I want an Excel spreadsheet that can be set to clients so that they can do their forecasting/budgeting and target setting.
It needs to be pretty sophisticated looking and deal with everything that needs to be dealt with but simple to use with clear report type pages.
It needs to be capable of forecasting both cashflow and PnL - but without the client having to input data twice.
It needs to be able to take account of monthly forecasting and target setting.
Thanks