The stamp is from a range called a Christmas Carol newly released by papermania. If you go to www.docrafts.co.uk there is a picture of it with a video explaining the range on the home page at the top. It should be available from any of your local docrafts stockists now and costs just £6-99 - The stamp is wood mounted and is approx 6x4 inches big. Sorry I can offer specific stockists as i bought mine from Embsay Mills and having checked their website click on crafts it is not on there as yet.
Good luck with the search!