Thank you JJ1 and Bushfiva.
The 'OTG' cable is 'On The Go' - one end has a mini USB and the other a USB female so you can plug card readers into the tablet. There is a file transfer app which allows transfer of card contents to the tablet - supposedly
but although I can get that working on the Nexus smart phone, it doesn't appear to work on the tablet
Have downloaded two different "File Managers" from Google Play or Shop or whatever it is, neither appear able to access the card contents. All this is probably down to my total failure to understand the Android concept ... sandwich shortage and picnics etc!!
If anyone understands what i am trying to achieve, simpleton-type advice would be greatly appreciated
TIA