Sorted it but thanks for the offer. For those in the future who find themselves in a similar position Pg13 of the manual in the link below lists the procedure:
https://manualzz.com/doc/6285581/service-manual#p13
Essentially I held the On Button (I) (with the hob off) until it cycled on and off. I then held the farthest right button (which on this model is the bridge function) and the space below and “do” appeared in the display. I then pressed the + key next to the clock and cycled to “d ” which switched demo mode off and it all functions perfectly.
Older AEG/Electrolux models seem to use the procedure listed on Pg18 of the manual in the link below this:
https://www.4mcculloch.co.uk/images/mediator/553/599519523.pdf
Hope that helps someone in the future