Thanks for your reply. Not sure which wall you are referring to? We can't block the bedroom that is next to the front door and we don't want people walking directly into the lounge. We also want the deck to be private. Do you mean to have the gate and doorbell outside in the open?

Go with crushed rock, and put enough down that you a have decent walkway or whatever, but not so much that you sink into it--you'll know the right depth when you get to it. Use a large rake to rake it out. We have that around our trees in the front mostly because the grass didn't grow under them, and our dogs run back and forth barking at the kids playing in the street. We found it to be a very good solution to the problem. And we did put scalloped edging bricks around the whole area.

The paving looks great. I'm normally against painting concrete but I think that's the answer here. Get a slightly darker colour than your paving. Plant some ground cover near the edges to soften the look.

I would consider a small retaining wall perhaps 2-3 planks high this will provide support to the bank but also allow the pathway to remain clear and formal. The ferns seem to be doing well but could do with a tidy up. I would also prune the tree so it allows a bit more light into the section to help prevent dampness, you also want to take it away from the house, without destroying it's natural shape. As ferns seem to naturally want to grow there, you could continue that theme. Perhaps some other shade / cooler temperature type plants with some flowers could be a good addition. I am not sure which plants can tolerate the cold Dunedin winters, so you best contact is your local garden centre. You want plants that are lush all year round. Also have a look at other plants growing in the neighbourhood as that will give you a good idea of what does and doesn't do well in your climate. Good Luck.