Some of thats easy to answer other bits not so much, Alcohol duty is £19.08 per 1% ABV per 100l theres up to 50% discount for small breweries, VAT is a 6th of the retail price and gets claimed back by anyone before the retail sale, ingredients grain costs £12-13 per Kg when buying by the ton no idea if you get much off buying more, hops range from £5 to £25 per KG, packing id minimal for kegs and casks small scale bottling or canning is about 50p per can or bottle if you pay a 3rd party to do it my guesstimate is about a third to a half that if you have an expensive bottling plant, energy not insignificant but lower than anything mentioned so far. As you can see you need to use a serious amount of expensive hops for the ingredients to get close to the duty cost. The main saving in larger scale is on labour.