Underlay for wood floor (Hailsham BN27)

I am looking for a small piece of thin underlay to allow me to extend a wooden floor into my understairs cupboard, rather than have to buy an entirely new roll. If anyone has any off cuts or ends of a roll they no longer need I am happy to tape pieces together to make a piece big enough to get to the required dimensions of approx 90cm x 2m. Many thanks!