John, go for it with regards to kitting the shed out as an alternative dwelling. My allotment she'd is currently a tin 7x8ft thing so not really much I can do there personally.
However I'm hoping this year to have an additional shed built to 10x8 size. The tin shed used for equipment & the new shed to be used as a home away from home. There's no mains loos but I'm hoping to have a compost loo there in the summer aswell.
Cooker wise, I've got myself a kitchen unit from a scrap trailer tent & it's twin hob, grill underneath & even has a kitchen sink, draining board, drawers & 2 small cupboards. I think it's the dogs dangly bits.
Runs off bottled gas but I'm also wanting a small woodstove to save the gas usage. Rather than a hammock, I'm planning on one of those high sleeper type beds so I have bed space but don't lose out on floor space. I'm not planning it as a BOL though, it'll be used for a little nap during days after my very early starts at work & my noisy neighbours doing their best to stop me sleeping. May I suggest, rather than a few windows, maplins do a mains free light kit. Solar powered, wiring kit, bulb holder & low energy 40w equivelant light bulb. All you need is a couple of car batteries to hold the power generated & you're good to go. With one of these, you'd only need 1 small window for ventilation as light would be sorted.
Ignore my window comment. Just re-read your post & seen you already have windows in place.