Hi Celeriac :)
It depends on your building skills, what materials you can get and how much
money you have available for the project, and most of all - what do you want to
have on your plot, a shed to stand in or a tool store?
Do you have a sound framework from the old shed, the bare bones?
You could re-clad it in woooden boards or use plastic for more light.
Do you have acccess to pallets (yay pallets ;D ) Which are a good source of
building material. Or any other reclaimed wood, If you have to build a frame from scratch you will need 6 or 8 feet long peices which I always find harder to get.
Don`t forget materials for a sound base.
If building a shed sounds daunting why not ask a shed-head on site I`m sure they`ll be happy to help / take-over.
You could manage without a shed, - I hear that people do :o and wait until you get get one from freecycle or similar. I would say do this job as soon as you can because you`ll be busier once the weather warms up.
Best of luck, Col