As far as I know, almost every Supermarket group has it's own speciality brand of quality bread.
These is made by a small group of speciality manufacturing bakers and, although not actually Artisan, are pretty good. However you can expect to pay about £1.50 - £2.00, for a 400 gram loaf. They arrive, at the Supermarket, par(t) baked and frozen, and are then finished in their In-house Ovens.
I currently buy brown Bloomers, they call them Organic but that is totally irrelevant, from both Morrisons and Tesco. (the Bloomer is an easier shape to cut)
If I happen to be passing through Prestwick, I will buy from one of the local Hoteliers who sells the products of his in-house bakery, but then I'm paying £2.50 for a 400 gram loaf.