Hi, if it’s to install an amendment 3 consumer unit, renew bonding to gas and water then to supply and fit you would be looking at around £400 labour and £150 parts. This installation would require an installation certificate and notification to your local building control. If the testing is completed thoroughly then it involves testing all of the hardwired circuit cables, it’s a good opportunity to find out the state of the installation at the same time. If you don’t already have a consumer unit with RCD protection then I strongly advise you upgrade. They offer you and your family unparalleled protection from a dangerous electric shock.