Ken, I had the same thought process as you three years ago, albeit on a smaller scale. Here are a few thoughts:
1. Every time you cut grass, you have green waste, it decomposes very well if mixed in with leaves/twigs.
Grass cuttings arise mainly in spring/summer, whereas leaves/twigs are abundant in late autumn. Collecting as much leaf/twig deposits now is a good storage strategy, ready to mix with grass you cut in spring/summer. I fill 10 or so green waste bags each autumn for use/storage.
2. Cardboard is good brown waste, I get free stuff from skips at a garden centre.
3. Garden waste (spent flowers etc), haulms from crops etc are good summer sources of green.
4. You can build a 1cubic metre pile of horse manure via three or four runs to a stables, using 4 council green waste receptacles to transport them in. Putting layers in a heap you build is very valuable.
Obviously, if you can find a farmer who will deliver you 5-10 tonnes of manure for a price, that is a huge difference.
But I manage to build 3 cubic metres of piles each growing season without such a dump, so there are ways to get started….although they finish up as around 1.2-1.5 cubic metres by maturity…..
The optional extras are comfrey plants, addition of rock dust and I control my yarrow plants by adding them to the heaps after they have been turned….
Hope this helps…..