You are getting that backyard back. Once this freestanding wooden garden shed kit is up, the mower, the soil bags, and the rusty tools finally have a home, and your garage floor is yours again. The actual build takes a weekend with a helper, but the secret is buying during late fall clearance sales at home centers when they want to clear inventory for winter.
Before you buy anything, get more than one quote for any site prep or permits you might need. Contractors and local handypersons price things differently, and checking two or three options keeps you from overpaying for a simple gravel pad or leveled ground.
That 0% window is a hard deadline, not free money. If you still carry a balance when the 18 months run out, the regular variable APR kicks in and you will start paying interest on what is left.