Hi and welcome.
It's an ideal opportunity to start to create something like this, but on a bigger scale, as I think your garden is at least twice as long as ours.
We've three quinces planted against the fence. The foliage forms a band about two feet high along the top part of the fence so hides a lot of it.
The rest is all azaleas and rhododendrons, one camellia and a couple of acer palmatums. Plus a few cyclamen in the front of the borders and a hell of a lot of bluebells. We hid the back fence with a bamboo forest (only a foot deep), there's a small acer and one of our five wisterias in front of it. A sambucus in a big tub hidden by more azaleas makes a central feature.
No bedding plants, haven't the time for them.
We avoided straight lines, a curved border makes it more interesting.
What you see is the result of a long term plan.
We've tried to make our garden as interesting as possible, by creating features that draw the eye as the garden is less than 90ft long and 30 feet wide at the maximum.
But it all takes time.