The airport is north of Oslo and if you are heading for Gjendesheim the quickest route will be through Hønefoss-Fagernes. Via Jaren and Dokka to Fagernes is slightly shorter but roads are not so good there.

https://media.snl.no/media/47719/standard_1_oppland-fylke-kart.png

There are hotels at Granavollen and in Jevnaker (Thorbjønrud), and in Hønefoss centre.

At Granavollen you can visit the Sister churches and the runestone (11th century tombstone)

https://www.visitostnorge.no/opplevelser/sosterkirkene-et-landemerke-p642143

https://en.wikipedia.org/wiki/Granavollen_stone

Jevnaker sits at eh south end of Randsfjorden lake and Dokka north end, Randsfjorden is one of the big lakes, and quite nice too

https://commons.wikimedia.org/wiki/File:Fluberg-Dokka-Norway-HH.jpg