Not very much to tell. It seems that the Norse and the Scots used to make a wine from the byproduct of their cheese making - the whey. Blaand does not mean "bland" as in tasteless but blond as in pale straw straw colored, which is how this wine finishes. Today whey is often viewed as a waste product but in the past cheese was made at home on crofts and farms but that was a very hard scrabble life and putting this whey to good use other than feeding it to farm animals would have been something that most crofters would have chosen and they made a wine from the by-product of their cheese making. Turns out that there are no published recipes that I have been able to locate as this was truly a folk product but about 15 years ago a fellow called Humphrey Errington who ran a dairy in Scotland started selling a drink he called Fallachan (Gaelic for hidden treasure) which was his version of blaand.
http://www.armchairanglophile.com/delicious-discovery-fallachan-blaand/ . A few years later he ran into some trouble with his cheese and sold the recipe to a brewery - Arran Brewery - that promised to continue making this wine but I can find no record that they did.
A few people are currently making this wine as home brewers: here's one being made in Orkney (Scotland)
. but this version uses acidified whey (using lemon juice or citric acid to clabber the milk) and not sweet whey that is produced by inoculating milk with cultures to create lactic acid from the lactose as you would when you make hard cheese). My guess is that the historical versions would have used sweet whey. Another possible way to make this wine today might be to use lactose free milk (yeast can ferment the sugars that result when you break down lactose), but you would need to acidify that milk to remove the calcium and other proteins from the milk otherwise the yeast will clabber the milk and you will get a soft cheese in your fermenter as well as the wine.
In my opinion, if you make blaand with sweet whey you need to boil the whey to kill the bacteria so that they don't continue to produce more lactic acid even as the yeast ferments added sugar.
Milk has perhaps 10- 20 points of sugar but that sugar is lactose and wine yeast cannot ferment lactose. My guess is that blaand likely had added sugars - honey, perhaps, or possibly barley sugars (malt). Or perhaps not. Perhaps traditionally it was about as alcoholic as kvass or khoumis.
I've made batches of blaand using both acidified whey and sweet whey (I make hard cheese). You might try adding say a pound of sugar or honey to every gallon of whey or you might make this closer to a wine by adding two or more pounds of fermentable sugars. I think whey has the nutrients that yeast need but you may want to add some tannin. I added some heather tips to my last batch.
The taste is ..um... unusual but if you are familiar with the taste of whey then it be so strange but as a wine it is a little different. It can taste quite refreshing but I think it tends to need a little back sweetening. You might try using lactose to back sweeten.