Setting up charities is quite straightforward these days, with the Charity Commission and others publishing model governing documents. There is no specific minimum turnover requirement for a new charity, but the Charity Commission will require evidence that the charity will be viable. They have thousands of dormant charities on the register. The relationship between the charity and the PC will need careful consideration, if the purpose of raising the funds is to support PC expenditure, as some of the projects may not be considered to be charitable within the Charity Commission definition. My parish charities are independent of the PC, apart from the PC having the right to appoint some trustees, but they are established with general grant-making powers that allow them to support any project for public good in the parish.
I suggest you contact your local branch of ACRE, the West of England Rural Network. They specialise in this type of work and would be in the best position to guide you through this one. They can also provide guidance on lotteries legislation and gift aid etc.