Not a shed exactly, but I bought a small summerhouse from solidsheds.co.uk - they have a display at Burleydam garden centre on the A41 so you can have a good look at the merchandise. It's certainly solid - good chunky timbers, seems very robust, and I'm happy with it. I had a concrete plinth done but if the ground is level you could probably set it on paving stones.
My son bought one of these sheds a couple of years ago. For storing high value (3k/4k) cycles. Cheap they are not! However, they are built like a brick outhouse and the locking mechanism and protected hinges are worthy of Fort Knox. Short of a gas axe, you ain't getting into one of these - without a key! As with anything, you get what you pay for. http://www.asgardsss.co.uk/?gclid=CMXcyd_W3MYCFSvItAodj3gOSQ