Posted: 20/08/2017 at 16:44
If it looks daunting then start on a small bit at a time, having made a basic plan of what you want.
Is it just the back you want advice about or the whole thing? I would start with the shed and where you want it exactly as you will need somewhere to keep your tools. Then I'd deal with the area nearest the house so you have something nice to look at and gradually move back as you deal with each bit. No need to rush in and do it all at once. It's quite long so you could divide it with trellis or a pergola for growing climbers and dividing it into "rooms".
Will you want vegetables? Most like a sunny spot.
As you have just moved you probably don't know what has already been planted. So there is something to be said for raisingirl's advice to wait and see what's going to come up, bulbs etc.
Keep the grass mown and existing beds weeded and have a look on the Internet, maybe buy a book about garden design and draw some designs to be thinking about.