I have used batting, Thermore and flannel on wearable quilt jackets - (not at the same time). I found the batting made it fairly bulky and somewhat stiff. I liked the flannel best, and as noted by others, definitely prewash and dry it.
The jacket with the batting was quilted through all three layers (outer, batting and lining) and then pieces cut out. The seams were bound and then the jacket was reversible. If I ever did this pattern again, I would use flannel as the filler.
As for the sleeves, I like a bit of quilting on them, but not so much it makes them stiff.
Sometimes I've used the flannel as the lining so there were only two layers to the jacket, and then used a twill tape to cover the seam allowances on the inside.
Good luck and please post your finished jacket. I really like the pattern you've chosen.