All gifts you leave to charity in your Will are free from inheritance tax. These gifts can be a specific amount or residuary, that is what remains in your estate after all taxes, bills, debts, and specific debts have been made.
You can use a solicitor, your bank or a Will writing company to help you leave a legacy to the NCKRF. If you made your Will a few years ago, it may be worth reviewing it to make sure that your wishes to leave a legacy are reflected