BOOKS YOU CAN PLAY WITH The main attraction of Go To Bed, Fred: A Good Night Book & Muppet Puppet is, of course, the Muppet: pale-blue Fred has a wild tuft of bright yellow hair, a lime-green nose and a wide mouth. The board book, by Alison Inches, illus. by Lauren Attinello, uses rhyme to show Fred getting ready for bed with a host of animal assistants: ""Hand me a towel, Baby Owl./ Time to floss, Albatross."" Sarah's House by Eric Thomas looks like an ordinary book, but tying the covers back to back with the attached ribbons turns it into a free-standing dollhouse with eight rooms, all set for occupation by a family of four press-out figures in Victorian dress (and their collie). While the floors are somewhat warped, the elaborate staircase, complete with landing and rails, rises with impressive solidity. Flaps open a mirrored medicine chest, a dollhouse, a standing wardrobe; movable doors connect the well-appointed rooms; and beds, bathtub, towel warmer and other furniture pop out in readiness. There are even chandeliers. Reader's Digest Young Families, meanwhile, offers two packaged sets that incorporate books into play. Teddy's Shop, a laminated box the size of a small shoebox, has a windowpane front that reveals its wares: three miniature 24-page books, a puzzle, a fold-out board game (with tokens nearly as large as the game), playing cards, stickers and a height chart (to measure the lack of growth of the reader's stuffed animals and toys). The set's centerpiece is a small, rather peevish-looking stoneware teddy figurine, which corresponds to the teddy bear hero of the books and toys. ($17.99 ages 6-up ISBN 0-88705-960-0, Nov.) A second Reader's Digest Young Families offering, I Can Stamp My ABC's includes more than 90 rubber stamps (of letters, numbers, shapes and pictures), stickers to label the stamps, a two-color ink pad, and six colored pencils. With the stamps, kids can complete pictures and answer questions in My First Stamp & Learn Book, an activity book by Doris Tomaselli, illus. by Cathy Beylon. Instructions leave little to the reader's imagination, telling not only what to stamp where, but what color to use: ""Stamp in Hoot Owl with a party hat and color the hat orange.""