Many thanks for the reply,interesting links.The system is for a friends language school where they want to log in the students for a lesson,so there's a record of them attending and a some way of rejecting the card if the card holder hasn't paid.A pretty basic system,I think.These might be ok for the card reader but I couldn't be sure how to write the cards or find a card supplier,but I notice the links you mention have this info so I'll have a closer look:
https://www.amazon.co.uk/s/ref=sr_pg_2?rh=i%3Aaps%2Ck%3Acard+swipe+reader&page=2&keywords=card+swipe+reader&ie=UTF8&qid=1472561934&spIA=B01ANDA8GE,B01EN9RP8S
Thanks again.Cheers