Never fished Yaddlethorpe ponds myself I'm afraid so can't help but it is day ticket and according to the local paper, fishing well.
However if you want a dead easy water, you could try Messingham Sands. Go past Yaddlethorpe ponds leaving Scunny. A couple of miles up the road you'll come to a X roads, turn right. About half a mile down there, there is a left turn down a gravel track. Immediately on your right is the Oak Tree Pond. Parking behind most pegs and its solid with fish. Gets popular at a weekend though. Next on the right is a match lake followed by two more day ticket waters, also on the right. There's some good fish in these with Carp and Cats topping 20 lb but there obviously not as easy as the Oak Tree Pond.
Day tickets are collected on the bank and I think they cost £5. Dawn to dusk fishing only.
If you don't fancy that, then carry on down the road another half mile and there's a day ticket pond opposite the driving range which has a good selection of species to go at. I think you have to get your tickets from the clubhouse but best check first.
Hope this helps.
Cheers
Ron