ah I see your issue then have you tried nick Lovett for a quote he is reasonably priced and only the other side of Newport he breaks landys too so may even have a clean bulkhead
From op's question, for less than the cost of a shipping container you could buy the timber/ zinc you need and knock together your own makeshift shed. Be wider and taller than a container too. But thats if you have the spare time too
Open doors on container 180 degrees,have a couple of posts in the ground to tie them to so they don't blow shut and kill you, health and safety Then knock up a frame that is the span of the doors fully open and as far forward of the container as you can get away with. Use some posts to hold the front edge up, have a slight tilt to it for rain water run off. Cover this with a tarp or something similar. Make some ramps for at the door way and get one of them ratchet hand winches for pulling it back up the ramps. Then you have a fairly spacious work area, which can all easily be packed away and locked up.