Above Video is an even simpler setup. will use the above method first.
Mini Biogas Digester Project Photo Gallery
http://bio-gas-plant.blogspot.com/2012/01/mini-biogas-digester-project-photo.html
Potential Equipment:
https://www.amazon.co.uk/BRTNUP-Collapsible-Container-Camping-Portable/dp/B0D2NXTJ7Q/ref=sr_1_42 – 20 litre portable water container as the gas storage tank – £4.99
To consider for later Biogas Tanks (Balloons):
https://www.alibaba.com/showroom/biogas-balloon_2.html?spm=a2700.7724857.0.0.57b51168hhL1H9
https://www.alibaba.com/product-detail/High-Quality-Leak-proof-Household-Foldable_1601160031151.html?spm=a2700.7724857.0.0.57b51168hhL1H9 – From about £30