Hello!
I’ve done a Debbie Bliss baby blanket for a friend that has various blocks of colours connected using the intarsia method. Looks great from the front, but awful from the back! 
I wondered if it would be possible to sew a fleece backing to it to cover up the “wrong” side, and if so, how would I go about doing this?
I’m a relative newbie to knitting and very much new to sewing. Any tips would be appreciated! Thank you!
One way to do this might be to just buy a soft flannel baby blanket, then align it with the back of yours and attach it by taking one of the yarn colors used in the front. You could thread a short piece of yarn on a sewing or yarn needle and pull it through both pieces and knot it decoratively on the back. You could also use embroidery floss. If you did this at say 6x6inch intervals, it should hold the back nicely. I once made a fabric quilt this way from an old woolen blanket using two pieces of fabric. You could overcast the edges to hold the sides together.
Great suggestions, thank you!