Something about how online shopping was pioneered goes here.
We can mention Armchair Grocer, from Club 403 on Prestel, 1984.
Michael Aldritch seems to crop up an awful lot in current media, e.g. http://www.bbc.co.uk/news/magazine-24091393 http://www.bbc.co.uk/news/business-24109101 which also quotes 1984. (and Rediffusion CVS logon screen 25 May 1984) but I would need some third party or contemporary sources to decide who really was “first”.
Gateshead MBC, Tesco Stores Plc and University of Newcastle have a “general shopping and information system” with an objective of providing a shopping service to the elderly, disabled and housebound.
Initial experiments on Prestel, new pilot phase started May 1984 using a Private Viewdata System running CVS on an ROCC R850. 25 customers; terminals in homes and central points in sheltered housing.