[Eibhlin ni Sheambrai]

Hi Athy, first thing to do is decide what this space is to be used for, growing things, sitting there, looking at from window, or a combination.
On the shady side you could mark how far out the shade extends and gravel this area and put pots on it. There are plenty of shade loving plants. Lidl have grass seed for shady areas advertised in todays brochure. There is a north facing clematis that would grow on the shed wall to disguise it.
Your 'head feature' sounds like the spirit of the garden watching over the space. Perhaps you could put some mesh or chicken wire around the drainpipe part and encourage sweet pea and/or nastursium to scramble up it. Both are a good investment as you can save the seeds and have more for the following year.
Ordinary concrete walls can be painted and/or covered in trellis--raid that ugly shed for things you can use!!
Bird feeders provide interest--again a wooden upright and cross bar will give plenty of places to screw in cup hooks for nuts, fat balls etc.
Wind chimes are fun and can be made from all sorts of things--raid that shed!!
Mirrors can provide depth and interest if set at an angle and give the impression of more to come.
Have fun and remember anything goes in the garden. Have a look at my blog in before&after for recycling tips in the garden. Eibhlin.