Wording your will
To ensure that your wishes are carried out as you intend, it is important that your Will is worded in the correct legal format. People often try to save money by using Will kits or their own wording of additions to an existing Will. But these are a false economy and carry a real risk of costing your relatives and executors far more in expenses, time and anxiety as they try to sort out the legal complexity of fulfilling your wishes. You should therefore always consult a professional adviser, such as a Solicitor with expertise in Wills and Probate. More information.
Parish or Diocese?
You can choose to leave a gift to either, but in both cases the gift has to be to the Trustees of the Diocesan Trust. This is because the Diocese is a registered charity and so can benefit from fact that legacies for charitable purposes are exempt from inheritance tax. (The Bishop is the senior Trustee of the Diocesan Trust.) But if you wish your parish to benefit, you can ask your Solicitor to use the particular wording which would enable this.
If you wish your legacy gift to support a particular project, it is best not to include this restriction in the wording of your Will, in case the project is no longer relevant when the time comes. An inappropriate restriction could mean your gift is invalid. It would be better to mention specific projects in a separate “Letter of expression of wishes” to your Executor.