NUMBER THREE in the UK supermarket league, Asda, has enlisted The Sun's recently launched CurrantBun.com free internet service to make its home shopping debut. Asda stores now offer customers free CD-Roms providing access to the service. Initially available on Asda's site are books, music and clothing, with other Asda lines due to come onstream at a later date. Although the supermarket giant has had its own internet site for some time, the joint venture marks its first foray into web-based home shopping. Trailing four weeks behind deadly rival The Sun, the Mirror Group has launched ic24, its free internet service with a claimed 50,000 pre-registered subscribers. MG also claims £1m of advertising support.