The best maps for exploring the Sandstone Trail are those published by the Ordnance Survey.
Two Explorer maps cover the Trail: 267 Northwich and Delamere Forest [North] and 257 Crewe and Nantwich [South].
However, if you buy the official guide, Walking Cheshire’s Sandstone Trail, you’ll find it contains large scale Ordnance Survey mapping of the whole Trail. In fact, the book contains the only maps you’ll need.