There are so many things that I loved about this book that I couldn't miss it out of this series of books and booze, but it's been by far the hardest to think of a match for. That's partly because one character is an alcoholic, and it always feels questionable to be recommending a drink if that's part of the context. It's also because whilst drinking is part of Shetland culture, pubs are not.
There are now a couple of breweries and a gin distillery, but the transport cost means the (very good) beers aren't especially easy to find outside of the islands (and definitely not this far south). One of the discount supermarkets (I can never remember which is which) was selling one of the Shetland Reel gins at a very good price, if you see it, buy it, it's an excellent gin, but it doesn't really capture the spirit of the book.
Malachy Tallack's characters drink all sorts of things throughout the book - tea especially, and that's possibly the drink I associate most with the Shetland that he's describing. They also drink all the other things ordinary people drink in the general way of things. If I think of what David, the older male character, or Maggie, the woman who's death opens the book would drink though the answer is probably McEwans Export (or Tennent's - both McEwan's and Tennent's cans were ubiquitous in every roadside ditch when I was a child) for David, and a whisky like The Famous Grouse or Bell's served in a thimble sized shot glass, possibly with a kilted bag pipe player, or sprig of Heather on it for either of them.
It's easy to be dismissive of blends like this these days, they're not especially fashionable, and somewhat looked down upon by a certain sort of whisky drinker - although they sell as well as ever. My preference is for Grouse, partly because I like the label, and love their adverts. Mostly because their blend has a good bit of Highland Park and the Macallan in it, both of which I'm especially fond of. It doesn't hurt that it comes with a bit of nostalgia for some sadly departed friends.
I'll admit I generally only have single malt in the house, and just as happily admit that sometimes that's a nuisance. I don't mind bathing my Christmas cake in Old Pultney, it's a once a year deal so it can drink whatever I'm having, but it's not really what I want to use for hot toddy's or whisky and ginger. Both of which are winter favourites, neither of which especially want the whisky to take over the mixer as say a Talisker or Lagavullin might. Nor do I want the particular subtleties of a precious bottle of whatever it might be drowned out by ginger, or honey and lemon.
The difference between blends and single malts isn't particularly one of quality. Until relatively recently you bought a blend precisely because it did guarantee quality and reliability. The grain element (which is cheaper to produce than the malt part because it's continuously distilled rather than pot stilled) forms a relatively light, smooth, background for the rest of the blend. Once you've found your preferred brand you should have something with a character you like, that balances nicely with your mixer of choice.
Something like proper thoughts about The Valley at the Centre of the World are Here. It has a lot to say about island living, tradition, people, love, and life generally and is absolutely worth having a look at.