That's going to be wonderful. Love the floor tile.
We have several places around here that build/sell sheds of all sizes; when I drive by them I often think they'd make a great place for a quilting haven. Around here, though, they'd have to be insulated and heated. Today's high was 5, right now it is 3 below zero. Come summer, it's hot and humid - so then I'd need air conditioning, lol.
Enjoy your new space; hope to see pics when it is done - the red trim sounds nice!