It appears that the Web site has been taken over by the devs for a phone app called CoolSudoku. All of the links on the tabs at the top of their page go to the site for the app (which has had pathetic ratings over the last 18 months). The daily and weekly competition puzzles (including archives) are still available as of this writing at the following links:
http://www.sudoku.org.uk/Daily.asphttp://www.sudoku.org.uk/jigsaw.asphttp://www.sudoku.org.uk/killersudoku.asphttp://www.sudoku.org.uk/WeeklySudoku.asphttp://www.sudoku.org.uk/WeeklyJigsaw.asphttp://www.sudoku.org.uk/WeeklyKiller.aspI did not check to see whether the puzzles are actually new, or just recycled. The Techniques page at
http://www.sudoku.org.uk/SolvingSudoku.asp also still works.
The Daily Minis (Sudoku and Killer), Hitori, Nurikabe, Kakuro, and Sudoku-X appear to be gone, as are all of their flash-based pages ( "Play Online", the "just for fun" Sudoku, Kakuro, and Jigsaw puzzles, the solvers, crosswords, and codewords). The "Future Puzzles" page for advance puzzles also appears to not be working. My guess is that once they get "enough" people submitting competition entries via the app, the entire site will go away, or else be devoted to just the paid puzzle packs and publication sales.