What to do with this corner of the garden?

Im struggling with what to do with this area of the garden.... It was where we had an 8 foot trampoline but now the kids are older its gone and going to be returned to a garden area. Its on a bit of a slope and is very wet - so wet that I dug a trench yesterday about a foot down to the clay and its filled up with a couple of inches of water since last night. So Im hiring a micro digger and am planning to put in some drainage and also remove some of the waterlogged soil and replace with fresh - ultimately then, it should be a blank canvas, the water should drain away and leave a decent area.
The space is:
3.3m from the back fence to the bricks(Depth) and 3.6m from the edge of the patio to the other fence(Width)
At the end of the raised border the little bit in there is 1.3m from the border to the bricks and 1.7m deep from the fence to the grass

What do I want? Not 100% sure and very open to ideas! I dont want a veg patch I want some height, just to add height to the garden and also to screen off the house behind. So Im thinking of a Strawberry Tree (Arbutus Unedo) for the back left corner then maybe something a little more upright, a Holly Tree maybe? Then in front of that.... Not sure - I really like those big deep borders filled with colour and different textures, so Im thinking leave the little slabs/stepping stones roughly where they are so I can get in and out and plant it up as a deep border. Do you guys thins that will work? What plants can you suggest for the big border - something cottage garden like, but never done planting like this before.
Im also debating removing the bricks and grass and bringing the border right out to where the lengths of wood are, I worry that the little square bit at the end of the raised bed will look small & lost and dont know what to do with it.
So - any and all ideas are welcome, the only things I want are a bit of height at the back and lots of colour/texture etc at the front

 

Hello Craig, welcome to GC. For specific plant advice, it would help us a lot to know whereabouts in the UK your garden is :-) My first thought on seeing the photos is that mowing must be pretty fiddly! I'd re-shape the lawn near the raised bed and edgings to give a gentle curve that is easy to follow. Then fill in gaps with plants. +1111 for Arbutus unedo 'Rubra'. Beautiful tree! Bear in mind that holly (and Mahonia, Berberis etc) drop vicious leaves. Not good for weeding under! As you're very sensibly sorting drainage and providing good soil, that'll open up lots of possibilities for a wide range of plants. We just need to know the area, which direction the beds face and whether you've got a microclimate....

 

Hi @Craig jameson , very exiting to have a blank canvas like that

If the corner gets sun, a huge Cordyline would give year round shape and height. We have some totally oversized ones in our office park and they are spectacular. Underplanting with something low and colourful, or big rocks... Then again, Arbutus Unedo is a superb tree so if you have a chance to get one, go for it.

Or, for something different, a small round pond would fit very well in a sloping situation. A small (solar powered) fountain to bring the sound of moving water is unbeatable. The Arbutus might fit behind for the height and being evergreen wouldn't drop too many leaves in. Different ferns around the pond and perhaps some upright flowering plants, Irises come to mind.

And in case of a grandkid or two appearing, the pond can become a sandpit before it's time for the second round of Trampoline.

 

Sorry should have mentioned, I'm in Central Scotland and the fence is south westish facing. I'm not too windy but certainly not sheltered but there are houses all around.

 

I have a pond at the other side of that back patio, there is a bit of a hill so I built that up and have a wee pond there, so this should just be planted

 

This is whats accumulated after 24hrs with no rain....