Yes it grows tall, but that’s not an issue next to a fence, the issue is the width!
There’s so much choice but this is fun to have a near blank canvas and I can tell your soil is good so you can do nearly anything.
I wouldn’t start at a garden centre. Borders are best when they are designed before you buy. Plus garden centres usually a rip off.
I would go on Instagram and have a look at pictures of borders, or google or Pinterest. If you find a picture I can tell you everything that’s in it and a shrub that would suit that style.
As your sedum is growing well maybe start there finding companions. You could have a browse on this site and see plants which grow with sedum. www.mariannemajerus.com/search?s=sedum*
All the names of the plants are listed below. The variety is just as important as the species so make sure to note that when you research. Imagine the species is the family name and the cultivar/variety the individual. So for example Prince ‘Harry’, Prince ‘Andrew’, Prince ‘Charles’ and Prince ‘William’ are all Princes. But they are all completely different - not just different looks, but different temperament, health and habits.
You can also look on the rhs plant directory. Choosing varieties with the rhs cup symbol means they are good happy plants.
Also crocus website is useful for sizes and flowering months, and has ‘goes well with’ suggestions.
Once you have a couple of flowers (so a colour scheme developing) and a couple of base plants like the grasses; then plot the pictures of the flowers blooming on an excel chart with the month as the column header. Then you can see where the flowering periods overlap and where you have gaps. Then try to find things to fill the gaps so you have something in bloom all summer. You can use bulbs to help fill these gaps too.
Anymore help just let us know 👌