I'm not sure how much of a market there is for Duplo on here but I have a big tub, including the yellow #5572
tub and I think #5575
as well. In addition there are quite a few bits including old style figures that I had as a kid in the late 70s. There's also some vehicle-type bits and doors.
I'm happy to deliver if you live near where I'm heading for work or you can collect from me in North Hertfordshire.