I've had no luck tracing this "A.W.Mc", I'm afraid, which is what I suspected. There is an "A.W. McDonald" that's listed as an artist that fits this time period, but very little is known about him other than the few signatures that appear on his paintings. Also, the style doesn't quite fit with that in your painting so I don't want to give the impression the two are definitely linked, but this is the closest I could come to a name.
It's certainly a very pleasing composition, a restful lacustrine and mountain scene in the Highlands of Scotland, it looks like, dating to the late 1800s, done by a competent hand and an academically trained artist. This is indicated by the use of what's called 'repoussior' features, the tall trees on the left hand side, deliberately placed to frame the composition and direct the eye towards the center of interest in the painting, namely the bright water and the figures in the small boat and the grazing cattle beyond. Another painterly 'trick' is the use of staffage, those two figures reclining by the water's edge, to give a sense of scale and perspective. Put your hand over them and all of a sudden it becomes so much harder to judge the distances.
The distant hills and the sky are also very carefully and convincingly done
All in all a lovely work with great tranquility and appeal. As for value, if you were to see it for sale in an antique store, it would have a full retail price tag of about $500. This is also the replacement value for insurance purposes.
I do hope this helps!