Snadger - I have used one of these and agree with others. They are too small to keep in all night. I have woodburners at home and they work great but the pot belly in the workshop needs to be fed every hour or it burns away. You can close the vent to make it last a bit longer but then you have to deal with quite a bit of smoke until the fire dies down. As to the size, the flue pipe on the top plate is about 100 / 150mm diameter so you can estimate the size of the stove in the picture from that.
Machine Mart
www.machinemart.co.uk do similar stoves.
Did you see the programme the other day about paying your mortgage off in 2 years? The bloke in question was making designer stoves from old calor gas bottles. Perhaps your welding and recycling skills may be used to create something from there.
Good luck.
PS
Found the web site
http://www.hotcreations.co.uk/aboutus.html
but you don't need anything as stylish s this for you greenhouse. If you did you would probably find it was pinched.