Hello Heidib,
could you give us the complete size of the area your thinking of putting a greenhouse please!

6ft wide is the norm for a smaller greenhouse, I wthinking maybe if you have the time you'd be better off getting intouch with one of the many poly-tunnel makers (gardening news adds) or use google and ask for poly-tunnel supply)
the idea being they'd make or maybe already have smaller sizes,

But before you spend any money on a greenhouse/tunnel make sure you have good space for both the sun to get in the g/house and you can walk around it for maintainance.
a good idea is if you can have water butts at each side for colletion of rain water 'very handy if water ban is in place and rain water is better than some tap water.

But if again you have a building or buildings causing a space reduction ?
Why not go for a greenhouse style "Lean-to"?

Hope this little lot helps.

have you tried your local paper often people give them alway for free or same price. sometimes you do have to take them down but it a cheap way to get a greenhouse.If you or any of your family are handy with a hammer you could knock up one of your own.we used recycled windows and now have a greenhouse and a sunny garden room cost about £20 for screws and some wood.You can paint all the windows to match so it does not look tacky.if you do try this i can give you some ideas.

i'd love a makeshift g/house out of real glass as the plastic walk in is a bit of pain nowadays (can't get replacement covers anymore and have had to patch it up with expensive gaffer tape instead.) Unfortunately, don't have anyone handy enough who could make me one though as I'd happily pay £50 for one from salvaged bits! I too, would need one that's less than 3' wide (length no problem) due to the narrow path I have in the small garden.

oh, i can just dream on instead!

Irridium, suppose you have a full width greenhouse but put a door at each end? We did this with a shed behind the garage once. The shed supplier was very surprised to be asked to replace the end wall with another door but it was just what we needed.

thanks for the tip. i've already had some thought on this and will be thinking about asking this guy i know who's doing a fence and gate for a friend of mine out of pallets. maybe with his handy resources, i can get him to make me a g/h with pvc windows and doors on the cheap?