All legacies left to charities are free of inheritance tax. Your solicitor can advise you on how to make your will as tax efficient as possible. There is no inheritance tax on specific charitable gifts in wills and they have tax advantages. Seek advice from your solicitor.
At present you can leave money free of inheritance tax up to £325K. Then for each £100 above this its £60 (60%) to friends & family & £40 (40%) to the Treasury.The tax is reduced to 36% if you leave more than 10% of your estate to charity.