You’re patio has a nice “sunken garden” vibe about it which I like.
I think the first thing is to work out what you want your garden to do for you. You’ve said you want a shed but do you want to eat outside or barbecue? And how much time do you want to spend gardening? What direction does it face? And then I’d go through some of the garden idea books on here and also search some terms like “sunken garden” and see what photos come up. When I do that it always leads me into other ideas that I wouldn’t have necessarily thought of on my own.

Hi Emily thank you for your feedback...My main seating areas and barbecuing will be on the patio and a second area for sun loungers just left of the tree on the grass...above the steps. I am not much of a gardener so ned sit to look after itself .. I am wanting bamboos in the 2 borders either side of the patio...but I do feel the top garden being so huge needs dividing somehow... perhaps even a tree planting in the middle.I want lush borders which need little maintenance. ...I will do as you say and do some more research . Thank you again.

Alison

Agree with Emily and take some time to gather ideas. A lush garden sounds lovely. This article had some nice ideas for planting https://www.houzz.co.uk/magazine/garden-tour-a-stunning-tropical-garden-before-and-after-stsetivw-vs~88336690 Be careful when choosing bamboo and get a non invasive or clumping variety, the spreading ones are ok in a container but can run amok if planted in the ground. I’d add a mix of plants which are easy maintenance, evergreen ornamental grasses, fatsia japonica, ferns, hostas, crocosmia...to name just a few.

A natural stone fire pit with suitable seating can make a real difference to a space like this. Either with permanent built structure or outdoor seating as in this photo. Perhaps make use of the wall of the sunken area?

A rockery could look really nice if it was in the right position

I would avoid a rockery too, we have one and we dig it over every few months thinking we are getting all the roots out...... and all the grass/weeds come back. Our rockery edges a lawn though which doesnt help of course!

Some good advice from Rachel above. Bamboo is wonderfully lush and creates a tropical wall of green but be very careful if you plan to plant directly into the ground. The roots will travel horizontally and pop up wherever they fancy ending up in neighbours gardens who won't be best pleased. If you do want to plant bamboo make sure its in large containers and feed it seaweed fertiliser to get it going and create the lush abundant foliage. It will also need plenty of regular water especially if its in a container. Once your shed is positioned in the right hand corner of your garden you could think about softening the side with planting. attach a trellis and grow a climbing clematis to blur the lines. Good luck and happy planting!

When we started doing our garden (it was landscaped, but in a pretty bad state), books by Tim Newbury were a tremendous help
Small Garden Design Bible https://www.amazon.co.uk/dp/0600616495/ref=cm_sw_r_sms_c_api_5IstAbJJ2EJ2C

I started with the one above, but he wrote a few, all of them very good, with easy to follow ideas and instructions.