I've been wanting to get my hair cut for a long time. I'm glad I finally went.
I had my hair cut today and I feel much better. I wanted to do that for such a long time.
この場合、次のような言い方ができます。
ーI've been wanting to get my hair cut for a long time. I'm glad I finally went.
「ずっと散髪に行きたかったから、やっと行けてよかった」
ーI had my hair cut today and I feel much better. I wanted to do that for such a long time.
「今日散髪してすっきりした。ずっと散髪したかったんだよね」
散髪してもらうことは to get one's hair cut や to have one's hair cut のように言えます。
ご参考まで！
カナダ 
