MY PRESSURE VALVE NEEDS REPLACING ON MY ALPHA CB 24 CAN I DO THIS MYSELF ?

MY ALPHA CB 24 HAS NOW BEEN OUT OF ACTION FOR A NUMBER OF WEEKS I HAVE BEEN TOLD THAT THE PRESSURE VALVE NEEDS REPLACING, IS THIS POSSIBLE TO DO MYSELF ?? IF NOT DOES ANYONE KNOW OF A PRICE RANGE TO GET THIS DONE OR ANYONE THAT CAN IN THE STOKE ON TRENT AREA IF YES PLEASE LEAVE DETAILS THANKS