Interest free credit

Hi there, I had a new kitchen fitted last year and intended to pay for it at the time using my AMEX card and then paying the full amount off before I was due any interest(avios points for a large sale). When I was just about to pay it I was offered a years interest free credit for 1 year which I took. That year is coming to an end and I am wondering if there is any way to pay for this but still get Avios points or Cashback. Does anyone know how I can pay this loan off which is with Barclays and get something back?
Thanks in advance