Underground Greenhouse.

[short circuit]

lol feel free yes I tend to try use old stuff to invent new stuff its saves loads of money I want a brazing kit so i can have a go at making a three seater peddal bike with trailer but with a motor on it for hills, I better not post about this here i kept going of topic bisty will be slapping me lol

[TwoDo]

I'll use whatever I can find however I can.

I always thought that if I needed to get a quantity of glass (cheap or free) for cloches or a homebrew green house I would go straight round to a double glazing installer. When they put in new windows they have to take the old ones away and I'm pretty sure they have to pay to dispose of them. There seemed to always be a pile of old windows out back of our local double glazing place whenever I looked.

It would be window glass rather than greenhouse glass but I expect it would do the job.

[short circuit]

Yes dubble glazing works well not as easy as it once was to get from window replacement firms but some might let you buy them. There also good for making solar heaters i.e. putting a black metal roofing sheet into a wooden frame and micro copper 10 or 12mm pipe coiled up the inside on the metal sheet then sprayed with fire black paint and covered with the glass panel. Cold water goes in and comes out boiling on a sunny day, trust me thay get it hot i burnt my hand testing out one i made when younger it comes out with steam.I think the summers we are getting in the uk starting to get more colder so I think anyone makeing a sunken greenhouse is moving in the right direction for a supplie of all year round food.

[Cocotte]

If you see anywhere with broken windows let them know that you'll happily take the glass away for free and hand them a note/card with your name, a number (& purpose ie glass collector). You can buy a glass cutter for £2-3 on amazon. Shops, bars, flats, estate/letting agents, newsagents window are prime places to put them up or hand in. Only problem may be getting too much after a while.
Then again, you can always extend the dig or DIY a double glaze for extra effect.