Cecilia,

Maybe this link is interesting? http://terrain.party/

1 - place the blue square over your target area
2 - use the + and - buttons at top-right to select area size (8-18 km2)
3 - use green button to select data source
4 - use down button to download data.
As far as I know all data sets include a grayscale height map (of varying quality)

Have fun.
BTW: the landscape is stunning!

Hans