There is another important thing to be said about this. The vowel after the soft "л" (л') in люк is not "у". When I hear foreigners speaking Russian I get the impression they are trying to say things like л'ук, and this is very difficult to do, and even if you succeed it won't come out right anyway. It's like trying to pronounce в'ыть instead of вить. The vowel in люк is almost as much different from "у" as "и" is different from "ы".