Whoever is named in the will as executor of your father's estate should seek probate. In the vast majority of cases, it's an incredibly simple process. I've done it myself with no problems. The staff at your local probate office will be helpful and can provide you with all the information you need.
To find your nearest probate registry, go here:
http://www.hmcourts-service.gov.uk/HMCSCourtFi nder/
Set 'Court Type', at the bottom of the page, to show 'Probate Court'. Click 'Find court'. Note that the resultant page is the first of two pages of information.
Chris