Then there are the Douglas Lindsay books, on which the film was based.

The books are very Glaswegian, very dark humor. They polarize readers into fans and haters.
I don't always get what's going on,
but when they make me laugh, they Really make me laugh.

These books have been written over a couple of decades by now.
There are Kindle/Internet versions with varied titles,
as well as the ink-and-paper type. The publishing has been
a challenge, and to his credit,
Douglas Lindsay won't give up, even when the business is frustrating.

The film was largely based on
"The Long Midnight of Barney Thomson,"
which is book number 1.

The other books, in order, are:
The Cutting Edge of Barney Thomson, also known
as The Barber Surgeon's Hairshirt.    a lot of FITBA' in that one

A Prayer for Barney Thomson, also known
as Murderers Anonymous.          Farewell to Glasgow, a lingering farewell, and a cliff-hanger ending kind of.

The King was in his Counting House, also known
as The Resurrection of Barney Thomson.          an Edinburgh caper.

The Last Fish Supper.                Scottish Riviera, island of Millport.

The Haunting of Barney Thomson.      Still on Millport.

The Final Cut.               mostly in London.

and now:
there is a book, just out, called
"Aye, Barney." So new there are no reviews.
I will let you know what I make of it
after my order shows up in the post.