I thought I'd do myself a test square, just so I knew what I was letting myself in for. After rereading the instructions, I had to take all my squares back to the sewing machine, they all needed to be top stitched!
Never mind now, it's all done, and I've done my test square. It looks so much better in real life, I can't wait to have more blocks. I think I'm going to blanket stitch and crochet as I go, it will be so much more fun seeing the pile of completed squares grow.