Thanks for all the suggestions & great advice.
The more I think about it, the more I realise what a big step it is for someone who has never been near a computer. Like just finding out what a wheel is and then being given the keys to a Lambo!
Must admit my first thought was an iPad (full size rather than mini though because of eyesight issues) as they are (fairly) easy to keep going and our family are all familiar with them so plenty of support.
Good suggestion of a trial run though as it is a big leap from quill pen to touch screen.
Common log in seems a good starting point as well.
Not sure how quickly (if ever) they will come to terms with internet banking and managing online energy accounts & bills? I will tread softly on that one, although they may surprise me!