Specialist garden centres stock bamboo up to a diameter of about 6" , I used some a few years to make a storage case for a pair of handmade salmon rods which was were sent out to Japan.
Thanks for the tip, I'd considered using flooring but really need continuous length of over 2m for this project. In the end I proposed using oak (quite a close colour match to the bamboo in question) but I think my price was too high and I never heard back!