I'm an employee at Robern-menz confectionary, manufacturers of amongst other things, Fruchocs and Crown Mints.
Our Chocolate making area generates a small amount of unused waste fat (Cocoa Butter and Hydrogenated Palm Oil) and I have started to collect this for future pickup and conversion to Biofuel. I'd estimate we'd fill a 20L drum with solid fat every month or so, (so maybe 10-15L of molten fat each month).
I'm hoping this fat is suitable for use as Biofuel and is in sufficient quantity to be useful for a home brewer.
We generate waste fat because we buy it in plastic wrapped blocks of 20 or 25Kg, fat gets stuck in the folds of plastic and falls to the floor when the block is removed from the plastic to be melted. So although it is unused, it is scraped from the floor so will contain some dust and dirt.
If you're interested, please PM me.