Are you sure that such a thing exists. Google seems to think not! (Even sites like eBay and Gumtree, including closed listings, seem not to know about it).
If you're certain that M&P used to stock Pooh, perhaps they might still have him lying at the back of a storeroom somewhere, waiting for someone like you to give him a home? Try asking them here:
https://www.mamasandpapas.com/en-gb/contact
1ozzy:
I found loads of links which looked that they might help but they all went to M&P's Pooh range of nursery furnishings (rather than to an actual soft toy) or alternatively to a soft toy not linked to M&P's.