Just had a quick coffee break and walk round the garden and I've realised that I can do this, and it reminded me why I'm doing this degree: I want to create gardens for people that lift their hearts, the way that my garden lifts mine (even in the desperate and neglected state it's in, but that can all be sorted out later).
And I do actually know what I'm doing, and for me, much of it is instinctive. As a designer, I need to make sure that I can communicate the reasons for my decisions so my clients have faith in me and recommend me to others. As long as you have a good understanding of the site, the client etc, the rest will follow.
So much still to do but I'm currently feeling optimistic (for now).
Just to prove that I did tidy my office, here's the after photo. It's currently somewhere between two.