I recently had a combi boiler installed and with the new pressure my old cistern system also needed updating to accomodate.
However the fill valve contantly drips when filled, is this normal or is it a easy fix i can do myself?
If it's one of these Torbeck Bottom-Entry Fill Valve 1/2" - Screwfix - https://www.NoLinkingToThis/p/torbeck-bottom-entry-fill-valve-1-2-/8120T?
you could try replacing the diaphragm washer that looks something like this?