The national tourist board is called VisitBritain. VisitBritain is the brand name of the British Tourist Authority. 

 VisitBritain have four websites to help visitors:

  •  www.visitbritain.com and lovewall.visitbritain.com are helpful resources in planning your trip to Britain, with many ideas on things to do, guides on different cities and regions, and an itinerary planner.
  •  www.visitbritainshop.com allows visitors to get transport and sightseeing tickets for their trip in advance of arriving in Britain. 
  •  www.visitbritain.org is their corporate website giving visitors information about the organisation. 

  

The local tourist offices in towns and cities are often listed under the local government website. These are www."nameoftown".gov.uk  if the town has a county council, e.g www.derbyshire.gov.uk .

Here is a link to Inside United Kingdom : Other UK Websites. It provides easy access to the numerous tourist websites across the UK.