your best option is to improvize, you may have to custom dye something, i dont know anything about fur avalibility in london, but the fur used on fozzie, as with most old scholl muppets is most likley no longer on the market, u have to keep inmind that fur like most fabrics is created mainly for use in the toy and garment industries, and as styles and technologies change so do the furs, the stuff used on fozzie was made in the seventies, and the fur was bought in bulk so that more than one could be built, what ever is left at the workshop, is most likley all that is left of it in the world, so i suggest you try to find a fur with a inch and a 1/2 pile , or maybe even longer then you could trim it to fit your puppet, u will also have to try and dy eit to match , but thier is no guarentee what you find will end up looking exactly like the original fur used,
sorry to be a buzz kill but such is life in the worl of puppet building materials change and as a puppet designer you have to change to work with the times.