Catch the train from Accrington to Entwistle. The Strawberry Duck
The Strawbury Duck | Turton, Bolton is right on the station. You can walk the 2.9 miles around the reservoir and have lunch in the pub. Dogs are allowed in the pub and they have a little room on the left with a couple of tables they ask you to use if your dog is dirty. The path around the reservoir is suitable for prams/pushchairs. There are often a couple of muddy puddles and the path is narrow are the far end of the res but I have been round with people with pushchairs.
If you want a slightly longer walk the res next to Entwistle is called Wayoh. It is 4.1 miles around it and the paths are not suitable for prams. A couple of short hill sections and some of it is through the woods.
If you want to drive there are a couple of car parks, stick Batridge Road, Bolton into your sat nav. I think the nearest postcode to the car parks is BL7 0EH
Both are lovely walks.