I have used a zigzag stitch on my regular sewing machine till I purchased the iron-on batting tape. Got a great deal when it was on sale plus they goofed and gave me an even large roll of it at that time. Just don't over lap the seams when you put them together. You'll have a lump.
When I chop off a section of batting from a freshly quilted top, I usually go ahead and tape it to a piece I've been adding to so its not just laying around. I then measure the entire piece and pin it to the batting and hang it up so I know how large it is.