What to put here - stones? Bark?

I have this area near my gas box. It used to be planted but was horribly overgrown.

I like the idea of putting stones down (you can see some on the daylight picture) but I read you need to put down a matting - and this is bad for the environment. I have some other areas with the matting down and weeds etc have sprung through over time.
I was thinking of using landscape bark for a clean-ish looking tidy effect.

Any suggestions please? Can bark just go straight down and will this suppress weeds?

 

Hi @MattKB - any gravel or bark will inevitably have weeds coming through, or seeding in, so you'd need to rake or pull out any that appear. You can certainly put a heavy layer of graevl down without the landscape fabric, but either way, weeds will appear. It isn't completely maintenance free.
However, the easier option is some low growing, ground covering plants - especially evergreen ones, which will be more attractive, and will do a better job of keeping weeds at bay, without interfering with the box itself. There are loads to choose from, depending on the aspect, and many will grow in almost any conditions. Saxifrages, Arabis, Aubrieta, Thyme, Ajuga etc.
You could also use some containers - planted up with different bulbs or perennials, and they could be moved when access is needed. As well as ones on the ground, you could even have a small 'table' which would cover the box, giving a bit of height, and allowing for other pots to be put on top. They're more work than plants in the ground though.

 

I wouldn’t put bark there, birds will redistribute it for you and it will be annoying! I’m not keen on gravel as it can also travel but larger materials like limestone chips, washed pebbles or slate can work in a small area. You could bed the pebbles into some mortar which can look attractive and be maintenance free.