Storage is the biggest question mark. In terms of actually laying out the equipment, you'd only need ~100 sqft for a three-vessel brewhouse, and ~50 sqft per fermenter to have a walkway on one side. In that size range, I'd assume you're looking at something like a semi-automated four head packaging line; that's another 150 sqft or so when it's set up. Call it 250 to allow for moving pallets around during packaging. So if you have 10 fermenters and two brights (1800-2600 bbl/yr capacity) you need ~1000 sqft for the brewhouse.
I don't know what the standard stacking height is over there, but it looks like a EUR pallet is about 10.3 sqft. Assuming 72 US cases per pallet, that's 0.5 bbl/sqft. So with 500 sqft of cold storage, you could hold about one month's production - two months if you can double-stack. That only leaves 500 sqft of dry storage, which isn't a whole lot but should let you keep at least 3-4 weeks of consumables in inventory, depending on what else you need to use it for.
In that production range, I'd say 2000 sqft is about the minimum. For what it's worth, we're looking at 1100 sqft for a 7 bbl system with no packaging, and I suspect we're still going to have to rent a storage unit.
