If you shop in sainsburys they do Cold milled flax seed. Milled or ground is all you need not necessarily flour. It is in the baking aisle but not right next to the whole flaxseed if your is anything like my sainsburys. Black and gold packet, 2 secs I'll go get it for the brand etc.......
Right its Virginia Harvest Cold milled Flaxseed. The gold is a bar across the top and there is a pic of a bowl of cereal and yogurt on the front with a spoon sprinkling flax onto it. It's £2 something for 175gs but you only need 30g for a Mim, mine has lasted a while as I don't have Mims that often. Hope that helps