Just spend a bit of time getting it sorted. Our Summer house is a million times better than the thing that was delivered, but I intended to insulate and line it. It also has a decking boarded floor, so the strength is there.
Don't rush.
This was June last year. It didn't exist in March (bear in mind I had broken my back and didn't get out of hospital until January). My wife had it delivered in late summer - we were still away at weekends at the caravan - when was I going to get it done. I had just about done a first treatment of base paint in the autumn on the parts (frames etc..), then thought about the decking layout, got the wood, then got bamm... back broken....
It's a basic shed/summer house, but we insulated it and ply lined it, decking was done first though. It's only 6x8 but we had 10 Teen girls in there between showers on my daughters birthday in June. WIFI booster and mains/USB charge points.. PS I had lots of help from my wife and kids.
It's a cheap (ish) summer house, but it took a fair amount to get it to a usable space, that will cost with any shed ! This was done on spare land at the side of our garden. Despite putting up a 'shed' the neighbours have all said how nice it is (it's partially in view).