You can go onto your local councils planning department website and there should be a local area map showing where permitted development rights have been removed.( especially if you are on a new build estate ) If so they will need approval for everything planned.
Hi I had exactly same situation as you have - an end of terrace with 2m gap. I decided to self build a lean to conservatory to use as a utility room and trawled Ebay and gumtree for years before I found one exactly the right dimensions ! 7.5m long x 2m width.
Entry is from the back garden but...
