Micro Biogas System?

To be honest - I don't think there IS an 'industry' right now. I have read of a few applications in developing countries mostly ad hoc throw together biomass cook stoves. That and large municipal methane digesters at sewage plants. Other than that I know of no company actively pursuing this in any commercial way for the household market.

If household waste isn't sufficient you might consider designs that would also be able to utilize yard waste - lawn clippings and such. Seasonal for sure but in much of North America the energy demand from air conditioning exceeds the heating demand in winter. Something probably not intuitive in Scotland.

Keep us posted.

The topic has been extensively discussed on CR4, from rural digester's, to commercial systems. Many of those discussions contain links to systems, approaches and equipment. Searching your key words in "all of CR4" (to the right of page), would be a useful first step.

You might find some good information from Mother Earth News. They have a good website.

What you are thinking is already in vogue in India. "Gobar-gas" plants can be seen in many villages using human and animal manure (Gobar in North Indian language).

it has to be community based and not for individual homes.