The path from Derry up to the hut is very good and easy walking. I walked the Lairig an Laoigh a few weeks ago and passed the hut before stopping near Glenmore lodge.
Lovely place to walk. You need to turn right before crossing the bridge at Derry Lodge as the bridge to get back over(Derry Dam, I think) is still in need of repairs. ( Doesn’t make much difference in time and you could cross the bridge if absolutely necessary)