Once probate has been granted you can write to the York Sub Probate Registry at Duncombe Place, York and request a copy. You will get a copy of the complete will and a copy of the Grant of Probate which includes figures for the gross and net estate. Send a cheque for £5 to HMPG (I think - but check on their website). Although note that for estates under the excepted estate limit (which I think is about £320k now, not sure without looking it up) the figures are not precise. Over that value and they are a much better indication.