I’ve seen a few floras for the British Isles, which probably has a similar flora. The boreal species really get around, so even North American guides, such as Irwin Brodo’s fabulous Lichens of North America might be very helpful, at least giving you an excellent overview of the genera present in Scandanavia. But a search on amazon.co.uk doesn’t show much explicitly for your area, I’m afraid.

(There’s one from 1994 by Santesson here. But I’ve never seen it — I suspect it’s a weighty technical flora — very cool that you live somewhere such a flora is available, but perhaps not the best book to start with if you aren’t already familliar with lichens!)

(PS. Looks like yours is probably in the Cladonia chlorophaea group, the so-called “mealy” pixie-cups.)