it's a wonderful first attempt and you're very brave to even attempt it. that said, i don't think you should add the fence until you soften this layer of work. i think it's important to work one layer at a time and then build up the next level as you would in an oil painting.
the grass is a little dense, imo, and it ends too abruptly at the top edge. using threadwork, i think it would benefit from 'tufts' sticking out over the top edge to soften the line. as others have said, the brickwork is a bit too strong in color. that's the first thing i saw when i looked at the work. the tulle could be useful there, maybe even two layers in a very muted color. or you could use a colorwash. don't be afraid of new techniques.
on the edges of the mountain, you could soften that with neutral threads, going back and forth to eliminate the hard edge and blend the color. when you see a mountain. you see lots of colors, not only one..
the tree is a little bright, but you can add some very pale grey thread to lighten it.
i'm not looking at this with a fibre artist's eye, so take this with a grain of salt. i'm seeing it with an art student's eye only. you have a very good basis to work with. it sounds like a lot of work, but it only needs threading, painting or ink highlights. the work is all there.
when you add the fence, add streaks of darker brown running lengthwise across the wood, as you would see it in nature. don't try to find the fabric for it. either use thread or fine pen.
remember, this is not not an exact copy of the cottage. the photo is the copy. this is your interpretation. you can add or subtract whatever you want to.
what's there is really good. build on top of it and follow your instincts. you can't make a mistake.